SIVA

Saturday, February 24, 2007

lamborghini gallardo

The Gallardo was designed as a competitor to Ferrari's 360 Modena, and now competes with its replacement, the F430. The car is named after a famous breed of fighting bull and is pronounced roughly "guy-ar-do". Gallardo is also Spanish for the word gallant. Although performance is lower than that of the Murcielago, it is still very high, and the Gallardo has much better rearward visibility (than the Murcielago) and, according to reviewers, is more maneuverable and tractable in low-speed traffic, making the Gallardo a more practical car to drive. It is also much more practical to use in bad weather than many other supercars, thanks to rear-biased all-wheel drive. Although corporate owner Audi[2] is renowned for its Quattro AWD system, Lamborghini uses a system of its own.

The Gallardo was designed by Belgian Luc Donckerwolk, who now works for Fiat.

At current U.S. prices, a base Gallardo costs about US$175,000.

The Gallardo uses a V10 engine based on Audi's old straight-5 design. The engine was split again to become the straight-5 engine found in the new Volkswagen Jetta. The 5.0 L engine (basically the same engine featured in Audi's S6 and S8 models) is a current Audi 4.2 L V8 (featured in Audi's S4, A6, A8, and Q7 models) with two extra cylinders added and a slightly smaller bore diameter.

The Gallardo offers two choices of transmissions, a conventional six-speed manual transmission, and an advanced six-speed electro-hydraulically controlled auto-clutch manual, or, as Lamborghini abbreviates it to, "E-gear". The latter allows the driver to make shifts much faster than an automatic transmission would, with the control that a manual offers. The driver shifts up and down via paddles behind the steering wheel, and does not need to manually actuate the clutch.

The Audi, R8 sports car, launched in early 2007, is based heavily on the Gallardo, but uses a V8 in place of the Gallardo's V10 to avoid competing directly with the Gallardo.

For the 2008 model year, the Gallardo will receive a slight facelift with a new front air dam, larger air intakes, dual squared of exhausts (similar to the Murciélago LP640) and new vents behind the front wheel. The Gallardo will also receive new rear suspension as well as a few other, unspecified components from the Audi R8[3]. To the disappointment of some Lamborghini fans, the Gallardo does not have "Jack Knife Doors," aka "Scissor Doors,"[1] as found on the Countach, Diablo, and Murcielago models.

[edit] Gallardo Spyder
Lamborghini Gallardo Spyders at the 2006 LA Auto Show
Lamborghini Gallardo Spyders at the 2006 LA Auto Show

The production spyder model of the Gallardo was unveiled at the Los Angeles Auto Show in January 2006. It is considered by the company to be an entirely new model, with 520 hp (388 kW) and a lower-ratio six-speed manual transmission. The soft top is fully retractable.

Aerosmith drummer Joey Kramer was the first person in North America to take delivery of the Gallardo Spyder.

Top Gear presenter Jeremy Clarkson announced on 18th February that he had bought one, replacing his Ford GT with a Gallardo Spyder.

[edit] Gallardo SE

In late 2005, the Gallardo SE (for Special Edition) was introduced. The SE is distinguished from the regular Gallardo externally by having a black-roofed two-tone color scheme as well as specially designed "Callisto" rims shod with Pirelli tires. Mechanically, the SE addresses many of the criticisms of the original Gallardo; the steering is quicker and more responsive, the transmission gear ratios have been adjusted to better suit the V10, and the E-gear now has a "thrust mode" to optimize acceleration, and the car's power has been increased to 520 hp (388 kW). The SE has a higher top speed of 315 km/h (196 mph), and it accelerates to 100 km/h in 4.0 seconds. Only 250 units of the Gallardo SE will be produced. All the mechanical upgrades of the SE, however, will be included in all Gallardos after 2006 (excluding the two-tone bodywork).
2006 Verde Ithaca Gallardo SE on Angeles Crest Hwy in Los Angeles.
2006 Verde Ithaca Gallardo SE on Angeles Crest Hwy in Los Angeles.
2006 Verde Ithaca Gallardo SE Interior.
2006 Verde Ithaca Gallardo SE Interior.

The Gallardo SE comes with a two-tone interior. All piping and stitching on the ultra-quality leather are executed in the same color as the bodywork of the car. The mid sections of the seats are finished in color-coded upholstery and even the black floormats have a color coded borders.

A rear-view camera is also standard issue on the Gallardo SE, as is a multimedia system and a navigation system. The sport suspension and an exclusive cover also came with the car but there are still several other options available, like the E-gear, which featured a 'thrust' mode to offer even more impressive acceleration by improving the gearchange through the different gears.

This "thrust" mode actually automatically revs the car to 5000 rpm, drops the clutch engaging all four wheels in a controlled burnout, and ensures the car performs maximum acceleration. This "launch" only requires the driver to engage the "thrust" mode and step on the gas pedal, similar to the launch technology in Formula 1 race cars.

[edit] Gallardo Nera

The Gallardo Nera (Special Edition) was introduced at Paris Motor Show. The Nera has a top speed of 315 km/h (196 mph), and it accelerates to 100 km/h in 4.0 seconds. Only 185 units of the Gallardo Nera will be produced and 60 are for the American market.[2]

[edit] Specifications
Lamborghini Gallardo in Nero Osyris
Lamborghini Gallardo in Nero Osyris
Performance
Top speed: 309 km/h (192 mph) / 315 km/h (196 mph)(Gallardo SE and 2006+)
0 to 100 km/h (62 mph): 4.2 s / 4.0 s (Gallardo SE and 2006+)
0 to 200 km/h (124 mph): 14.5 s
Standing km: 22.5 s
1/4 mile: 12.2 s at 118 mph(some SEs have run confirmed high 11s)
Engine
Type: V10
Displacement: 5.0 L
Power: 373 kW (500 bhp) / 388 kW (520 bhp) (Gallardo SE and 2006+)
Torque: 510 N·m

[edit] Trivia

* Gallardo is a breed of Canadian fighting bull. Nearly all of Lamborghini's cars are named after bulls.
* Bam Margera owns a purple Gallardo, which he cut a sunroof out of with the help of Billy Idol, which caused a large controvesy with Lamborghini enthuiasts.[citation needed] The clutch was destroyed by a crewmember on the 2006 Gumball Rally, which Margera was participating in. This amounted to an estimated US$15,000 worth of damage. In revenge, Margera threw paint and smashed the glass on the crewmember's Peugeot 306.[3]
* The Gallardo Spyder was road tested on the British TV show Top Gear where presenter Jeremy Clarkson described it as his new favourite supercar. According to the Top Gear magazine, Clarkson has ordered a Gallardo Spyder to replace his unreliable Ford GT. This was later confirmed in the Februrary 18, 2007 episode.
* In 2004, a stock yellow Gallardo coupe was piloted to 200 mph on a highway as part of the Super Speeders "1 Lap of NYC" street/drag racing video, exceeding the manufacturer's top speed estimate.
* One of the most highly modified Gallardo's (aesthetically) is the IMSA Gallardo created by German designer Holger Mohr. Featured on the January/February 2007 cover of Modified Luxury & Exotics magazine the widebody kit is made up of 18-pieces. A high-performance power package is in the works.[4]
* Undoubtedly, the most powerful Gallardo in existence belongs to Wayne Skiles. The twin turbo V10 built by Florida tuner shop Heffner Performance makes 679 hp and 475 ft-lbs of torque. It was featured in the July 2006 issue of Modified Luxury & Exotics magazine.[5]
* Currently, many young people are mislead to believe that the Gallardo is more powerful than the Murcielago. This however is untrue and is actually the fault of many racing games that give the Gallardo a higher top speed and acceleration level when compared to the Murcielago.
* Rapper Akon has mentioned this car, in his song "Smack That" featuring Eminem
* A Gallardo appears in the film Mission Impossible III.

[edit] Police car

In December 2004, several Gallardos were donated by Lamborghini to the Italian police in honor of the force's 152nd anniversary. The Gallardo Police Cars are used by the traffic police (Polizia Stradale) during emergencies and alarm situations on the Salerno-Reggio Calabria highway, also under the powers of the special safety operative which is already being employed along that tract of highway and above all, for the transport of body organs destined to transplants.

Yellow Gallardos have been "temporary" police cars for the Metropolitan Police in London, one in 2005 and one in 2006, for specific publicity events. The 2006 vehicle was seen at the start of the 2006 Gumball Rally. Both vehicles were loaned by Lamborghini London and were fitted with yellow and blue battenburg livery, police logos and a small blue lightbar.
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nissan

Concept
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After the Z32 was withdrawn from the U.S. market in 1996, Nissan initially attempted to keep the Z name alive by re-creating the 240Z the following year. The car was conceived by Nissan's North American design team in their free time, and the concept was introduced in a four-state Road Show in July 1998 to various car media, dealers and employees. Yutaka Katayama, regarded as the "Father of the Z", unveiled the Z concept sketch to the public when he received a motor industry award at the Ritz-Carlton hotel. The design, representing a modern vision of the 240Z, did not please the original 240Z designer Yoshihiko Matsuo, who compared it to the Bluebird and Leopard[2][3]

The first concept model was produced for the Detroit Motor Show for the following January then later at the Los Angeles Auto Expo. Nissan was unhappy with the first design. They felt that the original 200 bhp 2.4 L engine (known as the KA24DE) that was going to be assigned made the car more underpowered. They also felt that the car was considered too "retro" or too "backward" to resemble a futuristic 240Z, thus a redesign was under way. During a press conference in February 2000, President Carlos Ghosn gave the car the green light, as he felt the car would help to assist the company's recovery.[2]

The redesigned model, now known as the Z Concept, which was similar in body shape but with a redesigned front end, was unveiled at the Detroit Motor Show two years later. The car then underwent a minor redesign and was eventually assigned the VQ35DE engine, and the car became known as the 350Z. The car would break tradition by being the first Z not to be produced at the Shatai plant.[2]

[edit] Models
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Released on August 20, 2002, the 2003 350Z coupe was available in the U.S. in 5 trim packages, including the Base, Enthusiast, Performance, Touring, and Track Editions. In Europe only the Base version and a GT pack were sold. The GT pack had leather seats, Bose stereo system, and cruise control over the Base model. Nissan's performance tuning division, Nismo, began producing modified versions of the car shortly after its introduction, although in the UK these were only available one year after the car was launched.
Nissan 350Z roadster
Nissan 350Z roadster

In 2004 Nissan introduced the 350Z roadster featuring an electrically retractable soft-top hood. The car came in 2 trim packages (Enthusiast and Touring) in the U.S. market, and the Base and GT packs in Europe.

In 2005 Nissan launched a 35th Anniversary edition, which featured options such as "Z" emblems and 5-spoke wheels. The 2005 35th Anniversary edition 6-speed manual and 2005 Track trims both produce 300 hp and 296 torque (224 kW). In addition, The 35th Anniversary and Track 350Z also included revised pistons and camshaft profiles, and a new type of control to the variable valve timing. Although there were increases in power, the changes lead to a decrease in peak torque in the vehicle.

Nissan also added the Grand Touring trim to the Roadster trim packages for 2005. Since the anniversary edition all 6-speed models produce 300 hp / 260 ft·lb (224 kW / 353 N·m).

For the 2007 model year, the 350Z was moderately revised. The VQ35DE V6 was replaced with a new 3.5 L VQ35HR V6. It produced 306 hp at 6800 rpm with 268 lb-ft at 4800 rpm. The front bumper, hood, and headlamps were also revised with the hood featuring a bulge reminiscent of the original 240Z. Trims levels were also narrowed down to 350Z (base), Enthusiast, Touring, and Grand Touring.

[edit] Type-E

A limited run (only 5 units) called the Type-E was produced in Japan in order to meet homologation requirements to compete in the Super GT series. The Type-E featured a longer nose and rear overhang as well as a few extra aerodynamic aids.

[edit] S-Tune GT
Modified Nissan 350Z S-Tune GT at the 2006 Kuala Lumpur International Motor Show
Modified Nissan 350Z S-Tune GT at the 2006 Kuala Lumpur International Motor Show

The S-Tune GT was released by Nismo to celebrate its success in motorsport, particularly in the Super GT series. The S-Tune GT featured revised long nose bodywork as in the Type-E, a modified version of the VQ35DE engine called the S1 with more power (300 PS / 221 kW / 296 HP) and higher redline (7200 rpm), as well as a sportier Nismo suspension.

[edit] GT-S

During the 2006 Goodwood Festival of Speed, Nissan Technical Centre Europe (NTCE) unveiled the 350Z GT-S concept.[4] The GT-S featured a unique radial flow supercharger (that could be turned on or off via a switch on the dashboard), raising engine output to 382.6 bhp and 424.8 Nm without modifications to the engine components. The car also featured new body kit for more cooling and downforce and wider 245 and 265/40/18 tires. No plans for production have been revealed, although there have been some hints that the package may be offered as an upgrade kit. The car has been tested favorably against its possible production rivals, the Porsche Cayman S and BMW Z4 M.[5]

[edit] 450Z

Autocar reported rumors that Nissan was planning to release a 450Z coupe to rival the Porsche 911.[6] The car would feature a 4.5 L V8 engine, most likely a version of the VK45DE used in the Infiniti M45 and tuned to over 400 hp (300 kW), and all-wheel drive. The body would remain the same as that of the 350Z.

[edit] Alpine car

Another rumor is that the French brand Alpine (a manufacturer of Renault-powered sports cars) would be resurrected to offer a new car based on the platform of the 350Z, developed with the support of Porsche.[7]

[edit] Motorsport
Xanavi Nissan 350Z GT at the 2006 British International Motor Show
Xanavi Nissan 350Z GT at the 2006 British International Motor Show
Xanavi 350Z, rear
Xanavi 350Z, rear

Since its introduction in 2002, it did not take long for drivers and teams to enter a Z33 for competition when B.J. Zacharias and Michiel Schuitemaker of Schuitemaker Motorsports helped the car to make its debut in the Grand-Am Cup Series at the start of the 2003 season, they have took a few podium finishes with Unitech Racing who is also the other team to field a Z33, bit effort was proved to be successful under the name of Playboy Racing scoring wins along with the other current Grand-Am entrant East Competition Promotorsport.

The 350Z replaced the Skyline GT-R as the car for Nissan's factory and customer teams in the Super GT's GT 500 class. The cars used are heavily modified and feature a longer nose and tail (requiring the production of the Type-E homologation special), carbon fiber bodywork, tube chassis and a new, race tuned VQ30DETT engine. In 2004, Nismo won the GT500 championship. The car, with slightly more pedestrian modifications also competes in the GT300 class (having started there even before the Skyline GT-Rs were replaced) by teams such as Endless Sports and Mola. In 2003 Hasemi Sports won the GT300 championship with the 350Z..

The Z33 also appears in the Japan's Super Taikyu series, entered by C-West Labs. The British GT Championship also fields a privateer 350Z with an intention to enter the 24 Hours of Le Mans in 2006.

The car is considered popular choice for amateurs and professionals in SCCA events, T.C Kline took third place in the 2003 Touring 2 category in 2003, having being one of three Z33 that made it into the SCCA T-2 runoffs. In the SCCA GT2 class, Jim Goughary took the title it the car's debut season.

The car is used in import events and drifting, where in the latter, some drivers have started to use them in the D1 Grand Prix and Formula D series, with relatively limited results. However, at the 2006 D1GP exhibition event at the Las Vegas Motor Speedway, Tanner Foust became the first driver to score a perfect 100 points in a 350Z. In the non-Japanese domestic D1GP spinoff series, D1 Great Britain (D1GB), there are two Z33s that compete in the series.

Option magazine founder Daijiro Inada used an extensively modified 350Z, dubbed Option Stream Z to compete in the Silver State Classic Challenge.[8] The car is equipped with twin turbo-chargers and is bored to 3.8 L to produce over 800 bhp.

As the Z33 is popular in import drag racing, one Z33 fielded by Performance Motorsport in the NHRA Sports Compact series, with twin turbo claims to put out over 1700 bhp and achieved 8.33 quarter mile time with its best speed of 176.72 mph. In 2004, the tuner Dandy and magazine Option a Z33 entered a Z33 known as the Option Dandy 380Z with a donor engine from a wrecked Stream Z minus turbocharger producing 370 bhp, to compete in the F/GT class for unblown grand touring sport cars at the Bonneville Speed Week. The car could at best reach 151 mph.

[edit] In the media

The British Motoring magazine Top Gear voted the Nissan 350Z "Car of the Year" in 2004.[9]

The 350Z was also featured on the Top Gear TV program, where it was driven around the test track in a time of 1:31.8 - putting it level with the BMW M3 and the Mazda RX-8.

The car was also the vehicle driven by the villain "DK" in the movie The Fast and the Furious: Tokyo Drift, where it was styled with a VeilSide body-kit.[10]

The 350Z has also appeared in numerous motoring-based video games including: Need for Speed: Underground (in which it featured on the TV advert), Need for Speed: Carbon, Project Gotham Racing 2, Forza Motorsport (it features on the box cover), Sega GT2002 (also appears on the box cover of the Japanese version), Juiced, L.A. Rush, Test Drive Unlimited, Gran Turismo 3: A-Spec (as a concept car), and Gran Turismo 4 - of which a special, limited "Nissan 350Z edition" was released.[11]

The roadster 350Z is also driven by Edie Britt (played by Nicollette Sheridan) in the TV show Desperate Housewives.

The Autobot known as Prowl transforms into a Nissan 350Z in the 2006 Transformers: Infiltration comic.

[edit] Specifications
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2003-06 2007 Coupe 2007 Roadster
Available Trims 350Z (base), Enthusiast, Touring, Grand Touring Enthusiast, Touring, Grand Touring
Powertrain
Engine VQ35DE 3.5 L V6
287 hp at 6,800 rpm
260 lb-ft at 4,800 rpm VQ35HR 3.5 L V6
306 hp at 6,800 rpm
268 lb-ft at 4,800 rpm
Transmission 6-speed manual, 5-speed automatic
Dimensions
Curb Weight 3,339 lb (350Z)
3,346 lb (Enth)
3,400 lb (Tour)
3,404 lb (Grand) 3,580 lb (Enth)
3,600 lb (Tour)
3,602 lb (Grand)
Wheelbase 104.3 in
Length 169.8 in
Width 71.5 in
Height 52.1 in
Performance
0-60 mph
1/4 mile
Top speed

[edit] Criticism
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While the 350Z has received much praise in certain quarters, it has received a fair amount of criticism as well. Among the complaints are that the car is somewhat heavy, muting the sporty feeling during acceleration. The weight also means that, in order to handle like a sports car, the suspension must be extremely stiff, resulting in a very uncomfortable ride for many people. The lack of engine refinement and noise is also a major criticism. Other problems include:

* Poor quality of materials used on the interior and premature wear because of those materials.
* Lack of attention to ergonomic design,
* Glare given off the back strut bar that reflects in the rear view mirror
* Problems with the paint work have been reported on a number of vehicles, with paint coming off in a manner that suggests stone chips. Closer inspection of the paint work reveals that these defects are not caused by impacts on the paint work but rather from the paint cracking off in small patches. Nissan does not acknowledge this problem.
* Isolated, but widely reported issues with engines consuming their own oil at abnormal rates, more significantly in the 2006 "RevUp" edition of the VQ35 engine. Nissan currently is replacing engines that are brought in and found to consume 1 or more liters per 1000 miles, but has not issued a recall as of October 2006.

[edit] References

1. ^ Internet auto guide - Nissan 350Z specifications
2. ^ a b c Brian Long. (2004), Nissan 300ZX and 350Z: The Z-car story :Veloce. ISBN 1904788041
3. ^ Ron Sessions. (2002) Lust, Then Love: The Story of the New Z, :Publications International. ISBN 0785375686
4. ^ Nissan confirms production of 350Z GT-S.
5. ^ evo - Battle of the Sixes
6. ^ 350Z goes Porsche-baiting. Autocar. Retrieved on 2006-11-23.
7. ^ Renault to revive Alpine?. Reuters (2006-02-08). Retrieved on 2006-11-23.
8. ^ Roger Hewson (2004-10-25). Vengeance of the Z. Overboost.com. Retrieved on 2006-11-23.
9. ^ Top Gear Car of the Year 2004. CarPages.co.uk. Retrieved on 2006-12-15.
10. ^ Car of the Day:DK's 350Z. ign.com. Retrieved on 2006-12-15.
11. ^ Nissan 350Z Gran Turismo 4. Yahoo UK: Cars. Retrieved on 2006-12-15.

gamma ray

Gamma rays were discovered by the French chemist and physicist Paul Ulrich Villard in 1900, while he was studying uranium. Working in the chemistry department of the École Normale in rue d'Ulm, Paris with self-constructed equipment, he found that the rays were not bent by a magnetic field.

For a time, it was assumed that gamma rays were particles. The fact that they could be described as rays was demonstrated by the British Physicist William Henry Bragg in 1910, when he showed that the rays ionized gas in a way similar to X-rays.

In 1914, Ernest Rutherford and Edward Andrade showed that gamma rays were a form of electromagnetic radiation by measuring their wavelengths using crystal diffraction. The measured wavelengths were similar to those of X-rays and are very short, in the range of 10-11 m to 10-14 m. It was Rutherford who coined the name 'gamma rays', after having already named 'alpha' and 'beta' rays; the individual natures of the different rays were unknown at that time.

Gamma-ray astronomy did not develop until it was possible to get detectors above all or most of the atmosphere, using balloons or spacecraft. The first gamma-ray telescope, carried into orbit on the Explorer XI satellite in 1961, picked up fewer than 100 cosmic gamma-ray photons. Perhaps the most spectacular discovery in gamma-ray astronomy came in the late 1960s and early 1970s. Detectors on board the Vela satellite series, originally military satellites, began to record bursts of these rays, not from Earth, but from deep space. [1] Gamma rays have the highest frequency and highest amount of energy on the EM spectrum (elctromagnetic spectrum). Gamma rays also have the shortest wavelength out of all the waves on the EM spectrum

[edit] Properties

[edit] Shielding

Shielding for gamma rays requires large amounts of mass. The material used for shielding takes into account that gamma rays are better absorbed by materials with high atomic number and high density. Also, the higher the energy of the gamma rays, the thicker the shielding required. Materials for shielding gamma rays are typically illustrated by the thickness required to reduce the intensity of the gamma rays by one half (the half value layer or HVL). For example, gamma rays that require 1 cm (0.4 inches) of lead to reduce their intensity by 50% will also have their intensity reduced in half by 6 cm (2½ inches) of concrete or 9 cm (3½ inches) of packed dirt.

[edit] Matter interaction
The total absorption coefficient of aluminium (atomic number 13) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Over most of the energy region shown, the Compton effect dominates.
The total absorption coefficient of aluminium (atomic number 13) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Over most of the energy region shown, the Compton effect dominates.
The total absorption coefficient of lead (atomic number 82) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Here, the photo effect dominates at low energy. Above 5 MeV, pair production starts to dominate
The total absorption coefficient of lead (atomic number 82) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Here, the photo effect dominates at low energy. Above 5 MeV, pair production starts to dominate

When a gamma ray passes through matter, the probability for absorption in a thin layer is proportional to the thickness of that layer. This leads to an exponential decrease of intensity with thickness

I(d) = I_0 \cdot e ^{-\mu d}

Here, μ = n×σ is the absorption coefficient, measured in cm−1, n the number of atoms per cm3 in the material, σ the absorption cross section in cm2 and d the thickness of material in cm.

In passing through matter, gamma radiation ionizes via three main processes: the photoelectric effect, Compton scattering, and pair production.

* Photoelectric Effect: This describes the case in which a gamma photon interacts with and transfers its energy to an atomic electron, ejecting that electron from the atom. The kinetic energy of the resulting photoelectron is equal to the energy of the incident gamma photon minus the binding energy of the electron. The photoelectric effect is the dominant energy transfer mechanism for x-ray and gamma ray photons with energies below 50 keV (thousand electron volts), but it is much less important at higher energies.

* Compton Scattering: This is an interaction in which an incident gamma photon loses enough energy to an atomic electron to cause its ejection, with the remainder of the original photon's energy being emitted as a new, lower energy gamma photon with an emission direction different from that of the incident gamma photon. The probability of Compton scatter decreases with increasing photon energy. Compton scattering is thought to be the principal absorption mechanism for gamma rays in the intermediate energy range 100 keV to 10 MeV (megaelectronvolts), an energy spectrum which includes most gamma radiation present in a nuclear explosion. Compton scattering is relatively independent of the atomic number of the absorbing material.

* Pair Production: By interaction via the Coulomb force, in the vicinity of the nucleus, the energy of the incident photon is spontaneously converted into the mass of an electron-positron pair. A positron is the anti-matter equivalent of an electron; it has the same mass as an electron, but it has a positive charge equal in strength to the negative charge of an electron. Energy in excess of the equivalent rest mass of the two particles (1.02 MeV) appears as the kinetic energy of the pair and the recoil nucleus. The positron has a very short lifetime (if immersed in matter) (about 10-8 seconds). At the end of its range, it combines with a free electron. The entire mass of these two particles is then converted into two gamma photons of 0.51 MeV energy each.

The secondary electrons (or positrons) produced in any of these three processes frequently have enough energy to produce many ionizations up to the end of range.

The exponential absorption described above holds, strictly speaking, only for a narrow beam of gamma rays. If a wide beam of gamma rays passes through a thick slab of concrete, the scattering from the sides reduces the absorption.

Gamma rays are often produced alongside other forms of radiation such as alpha or beta. When a nucleus emits an α or β particle, the daughter nucleus is sometimes left in an excited state. It can then jump down to a lower level by emitting a gamma ray in much the same way that an atomic electron can jump to a lower level by emitting visible light or ultraviolet radiation.
Decay schema of 60Co
Decay schema of 60Co

Gamma rays, x-rays, visible light, and UV rays are all forms of electromagnetic radiation. The only difference is the frequency and hence the energy of the photons. Gamma rays are the most energetic. An example of gamma ray production follows.

First 60Co decays to excited 60Ni by beta decay:

{}^{60}\hbox{Co}\;\to\;^{60}\hbox{Ni*}\;+\;e^-\;+\;\overline{\nu}_e.

Then the 60Ni drops down to the ground state (see nuclear shell model) by emitting two gamma rays in succession:

{}^{60}\hbox{Ni*}\;\to\;^{60}\hbox{Ni}\;+\;\gamma.

Gamma rays of 1.17 MeV and 1.33 MeV are produced.

Another example is the alpha decay of 241Am to form 237Np; this alpha decay is accompanied by gamma emission. In some cases, the gamma emission spectrum for a nucleus is quite simple, (eg 60Co/60Ni) while in other cases, such as with (241Am/237Np and 192Ir/192Pt), the gamma emission spectrum is complex, revealing that a series of nuclear energy levels can exist. The fact that an alpha spectrum can have a series of different peaks with different energies reinforces the idea that several nuclear energy levels are possible.
Image of entire sky in 100 MeV or greater gamma rays as seen by the EGRET instrument aboard the CGRO spacecraft. Bright spots within the galactic plane are pulsars while those above and below the plane are thought to be quasars.
Image of entire sky in 100 MeV or greater gamma rays as seen by the EGRET instrument aboard the CGRO spacecraft. Bright spots within the galactic plane are pulsars while those above and below the plane are thought to be quasars.

Because a beta decay is accompanied by the emission of a neutrino which also carries energy away, the beta spectrum does not have sharp lines, but instead is a broad peak. Hence from beta decay alone it is not possible to probe the different energy levels found in the nucleus.

In optical spectroscopy, it is well known that an entity which emits light can also absorb light at the same wavelength (photon energy). For instance, a sodium flame can emit yellow light as well as absorb the yellow light from a sodium vapour lamp. In the case of gamma rays, this can be seen in Mössbauer spectroscopy. Here, a correction for the energy lost by the recoil of the nucleus is made and the exact conditions for gamma ray absorption through resonance can be attained.

This is similar to the Franck Condon effects seen in optical spectroscopy.

[edit] Uses

The powerful nature of gamma rays has made them useful in the sterilization of medical equipment by killing bacteria. They are also used to kill bacteria and insects in foodstuffs, particularly meat, marshmellows, pie, eggs, and vegetables, to maintain freshness.

Due to their tissue penetrating property, gamma rays/X-rays have a wide variety of medical uses such as in CT Scans and radiation therapy (see X-ray). However, as a form of ionizing radiation they have the ability to effect molecular changes, giving them the potential to cause cancer when DNA is affected.

Despite their cancer-causing properties, gamma rays are also used to treat some types of cancer. In the procedure called gamma-knife surgery, multiple concentrated beams of gamma rays are directed on the growth in order to kill the cancerous cells. The beams are aimed from different angles to focus the radiation on the growth while minimizing damage to the surrounding tissues.
The Moon as seen in gamma rays by the Compton Gamma Ray Observatory. Surprisingly, the Moon is actually brighter than the Sun at gamma ray wavelengths.
The Moon as seen in gamma rays by the Compton Gamma Ray Observatory. Surprisingly, the Moon is actually brighter than the Sun at gamma ray wavelengths.

Gamma rays are also used for diagnostic purposes in nuclear medicine. Several gamma-emitting radioisotopes are used, one of which is technetium-99m. When administered to a patient, a gamma camera can be used to form an image of the radioisotope's distribution by detecting the gamma radiation emitted. Such a technique can be employed to diagnose a wide range of conditions (e.g. spread of cancer to the bones).

Gamma ray detectors are also starting to be used in Pakistan as part of the Container Security Initiative (CSI). These US$5 million machines are advertised to scan 30 containers per hour. The objective of this technique is to pre-screen merchant ship containers before they enter U.S. ports.

[edit] In popular culture

* Exposure to gamma rays transformed the scientist Bruce Banner into the Incredible Hulk in the Marvel comic of the same name; many of the Hulk's villains and allies also attained their superpowers through this method. It is a recurring theme in Marvel stories that mutations caused by gamma radiation often unleash some hidden aspect of the affected person's psyche; for example, the raging Hulk is a manifestation of Banner's repressed emotions and violent tendencies stemming from an abusive childhood. In his ending of the non-canon Marvel Super Heroes vs. Street Fighter, The Hulk theorizes that gamma radiation caused Blanka's mutations, as they did his. [2]
* In both Gundam Seed and Seed Destiny gamma ray technology is incorporated in the space cannon G.E.N.E.S.I.S.(Gamma Emission by Nuclear Explosion Stimulate Inducing System); a huge gamma-ray laser canon.
* In David Weber's Honorverse, grasers are powerful gamma-radiation-powered energy weapons.
* Metroids, creatures in the popular series of the same name, go through a large metamorphosis when exposed to gamma-radiation.

[edit] Health effect

The gamma rays are the most dangerous radiations emitted by a nuclear bomb because of the difficulty of their stopping. Gamma-rays are not stopping by the skin.

They can induce DNA alteration by interfering with the genetic material of the cell. DNA double-strand breaks are generally accepted to be the most biologically significant lesion by which ionizing radiation causes cancer and hereditary disease [3].

A study done in Russian nuclear workers exposed to external whole-body gamma radiation at high cumulative doses shows the link between radiation exposition and death from leukaemia, lung, liver, skeletal and other solid cancers [4].

Alongside with radiation, gamma-rays also produce thermal burn injuries, but also induce an immunosuppressive effect [5], [6]

[edit] Body response

After gamma-irradiation, and the breaking of the DNA double-strands, the cell can repair the damaged genetic material in the limit of his capability.

However, a study of Rothkamm and Lobrich [7] has shown that the repairing works well after high-dose exposure but is really slower in the case of a low-dose exposure.

It could mean that a chronic low-dose exposure could not be fought by the body.

[edit] Risk assesment

The natural outdoor exposition in Great Britain is in the range 20-40 nSv/h [8]. Natural exposition to gamma rays is about 1 to 2 mSv a year, and the average total amount of radiation received in one year per inhabitant in USA is 3,6 mSv [9].

To compare, the radiation dose from chest radiography is a fraction of the annual naturally occurring background radiation dose [[10]], and the dose from fluoroscopy of the stomach is, at most, 0.05 Sv on the skin of the back.

For acute full body equivalent dose, 1 Sv causes slight blood changes, 2-5 Sv causes nausea, hair loss, haemorrhage and will cause death in many cases. More than 3 Sv will lead to death in less than two months in more than 80% of cases, and much over 4 Sv is more likely than not to cause death [11].

For low dose exposure, for example in nuclear workers population who receive an average radiation of 19mSv, the risk increase by 2 percent in that worker's risk of dying from all cancers excluding leukaemia. For a dose of 100mSv, that risk increase is at 10 percent. In comparison, it was 32% for the Bomb-A survivors [12].

beta decay

beta decay is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. In the case of electron emission, it is referred to as "beta minus" (β−), while in the case of a positron emission as "beta plus" (β+).

In β− decay, the weak interaction converts a neutron (n0) into a proton (p+) while emitting an electron (e−) and an anti-neutrino (νe):

n^0 \rightarrow p^+ + e^- + \bar{\nu}_e.

At the fundamental level (as depicted in the Feynman diagram below), this is due to the conversion of a down quark to an up quark by emission of a W boson.

In β+ decay, a proton is converted into a neutron, a positron and a neutrino:

\mathrm{energy} + p^+ \rightarrow n^0 + e^+ + {\nu}_e.

So, unlike beta minus decay, beta plus decay cannot occur in isolation, because it requires energy, the mass of the neutron being greater than the mass of the proton. Beta plus decay can only happen inside nuclei when the absolute value of the binding energy of the daughter nucleus is higher than that of the mother nucleus. The difference between these energies goes into the reaction of converting a proton into a neutron, a positron and a neutrino and into the kinetic energy of these particles.

In all the cases where β+ decay is allowed energetically (and the proton is a part of a nucleus with electron shells), it is accompanied by the electron capture process, when an atomic electron is captured by a nucleus with the emission of a neutrino:

\mathrm{energy} + p^+ + e^- \rightarrow n^0 + {\nu}_e.

But if the energy difference between initial and final states is low, the electron capture can occur without being accompanied by positron emission.

If the proton and neutron are part of an atomic nucleus, these decay processes transmute one chemical element into another. For example:

\mathrm{{}^1{}^{37}_{55}Cs}\rightarrow\mathrm{{}^1{}^{37}_{56}Ba}+ e^- + \bar{\nu}_e (beta minus),

\mathrm{~^{22}_{11}Na}\rightarrow\mathrm{~^{22}_{10}Ne} + e^+ + {\nu}_e (beta plus),

\mathrm{~^{22}_{11}Na} + e^- \rightarrow\mathrm{~^{22}_{10}Ne} + {\nu}_e (electron capture).

Historically, the study of beta decay provided the first physical evidence of the neutrino. In 1911 Lise Meitner and Otto Hahn performed an experiment that showed that the energies of electrons emitted by beta decay had a continuous rather than discrete spectrum. This was in apparent contradiction to the law of conservation of energy, as it appeared that energy was lost in the beta decay process. A second problem was that the spin of the Nitrogen-14 atom was 1, in contradiction to the Rutherford prediction of ½. In a famous letter written in 1930 Wolfgang Pauli suggested that in addition to electrons and protons atoms also contained an extremely light neutral particle which he called the neutron. He suggested that this "neutron" was also emitted during beta decay and had simply not yet been observed. In 1931 Enrico Fermi renamed Pauli's "neutron" to neutrino, and in 1934 Fermi published a very successful model of beta decay in which neutrinos were produced.

Beta decay does not change the number of nucleons A in the nucleus but changes only its charge Z. Thus the set of all nuclides with the same A can be introduced; these isobaric nuclides may turn into each other via beta decay. Among them, several nuclides (at least one) are beta stable, because they present local minima of the mass excess: if such a nucleus has (A, Z) numbers, the neighbour nuclei (A, Z−1) and (A, Z+1) have higher mass excess and can beta decay into (A, Z), but not vice versa. It should be noted, that a beta-stable nucleus may undergo other kinds of radioactive decay (alpha decay, for example). In nature, most isotopes are beta stable, but a few exceptions exist with half-lives so long that they have not had enough time to decay since the moment of their nucleosynthesis. One example is 40K, which undergoes all three types of beta decay (beta minus, beta plus and electron capture) with half life of 1.277×109 years.

Some nuclei can undergo double beta decay (ββ decay) where the charge of the nucleus changes by two units. In most practically interesting cases, single beta decay is energetically forbidden for such nuclei, because when β and ββ decays are both allowed, the probability of β decay is (usually) much higher, preventing investigations of very rare ββ decays. Thus, ββ decay is usually studied only for beta stable nuclei. Like single beta decay, double beta decay does not change A; thus, at least one of the nuclides with some given A has to be stable with regard to both single and double beta decay.

Beta decay can be considered as a perturbation as described in quantum mechanics, and thus follows Fermi's Golden Rule.

alpha decay

radioactive decay in which an atomic nucleus ejects an alpha particle through electromagnetic force and transforms into a nucleus with mass number 4 less and atomic number 2 less. For example:

{}^2{}^{38}_{92}\hbox{U}\;\to\;{}^2{}^{34}_{90}\hbox{Th}\;+\;{}^4_2\hbox{He}^{2+},

although this is usually written as:

{}^{238}\hbox{U}\;\to\;^{234}\hbox{Th}\;+\;\alpha.

(The second form is also preferred because, to the casual observer, the first form appears electrically unbalanced. Fundamentally, the recoiling nucleus is soon stripped of two electrons to neutralize the hungry helium cation.)

An alpha particle is a helium nucleus, and both mass number and atomic number are conserved. Alpha decay can essentially be thought of as nuclear fission where the parent nucleus splits into two daughter nuclei. Alpha decay is fundamentally a quantum tunneling process. Unlike beta decay, alpha decay is governed by the strong nuclear force.

Alpha particles have a typical kinetic energy of 5 MeV (that is ≈0.13% of their total energy, i.e. 110 TJ/kg) and a speed of 15,000 km/s. This corresponds to a velocity of around 0.05c. Even so, they are often absorbed within a few centimetres of air.

Because of alpha decay, virtually all of the helium produced on Earth comes from trapped underground deposits associated with minerals containing uranium or thorium, and brought to the surface as a by-product of natural gas production.

[edit] History

By 1928, George Gamow had solved the theory of the alpha decay via tunnelling. The alpha particle is trapped in a potential well by the nucleus. Classically, it is forbidden to escape, but according to the then newly discovered principles of Quantum mechanics, it has a tiny (but non-zero) probability of "tunneling" through the barrier and appearing on the other side to escape the nucleus.

[edit] Toxicity

Alpha particles emitted by radioactive nuclei are among the most hazardous forms of radiation if these nuclei are incorporated within a human body. As any heavy charged particle, alpha particles lose their energy within a very short distance in dense media, causing significant damage to surrounding biomolecules. On the other hand, external alpha irradiation is not harmful because alpha particles are completely absorbed by a very thin (micrometers) dead layer of skin as well as by a few centimeters of air. However, if a substance radiating alpha particles is ingested, inhaled by, injected into, or introduced through some skin-penetrating object (shrapnel, corrosive chemicals) into an organism it may become a risk, potentially inflicting very serious damage to the organisms' genetic makeup.

One common source of alpha radiation is radon, a naturally occurring, radioactive gas found in soil, rock and sometimes groundwater. When radon gas is inhaled, some of the radon gas and its associated decay particles stick to the inner lining of the lung. The decay particles that remain after the air is exhaled will continue to decay over time, damaging the lung's sensitive tissue.[1] Shrapnel from depleted uranium poses another such risk of alpha-emitters.

The death of Marie Curie was caused by leukemia from exposure to alpha emitters such as radium during her years of work.

The 2006 death of Russian dissident Alexander Litvinenko is thought to be due to his being poisoned with polonium-210, an active alpha emitter.

nuclear fusion

In astrophysics, fusion reactions power the stars and produce all but the lightest elements. Whereas the fusion of light elements in the stars releases energy, production of the heaviest elements absorbs energy, so that it can only take place in the extremely high-energy conditions of supernova explosions. In technical applications, fusion of light elements provides the energy of thermonuclear explosions and, if all goes well, someday also that of fusion power.

It takes considerable energy to force nuclei to fuse, even those of the lightest element, hydrogen. But the fusion of lighter nuclei, which creates a heavier nucleus and a free neutron, will generally release more energy than it took to force them together — an exothermic process that can produce self-sustaining reactions.

The energy released in most nuclear reactions is much larger than that for chemical reactions, because the binding energy that holds a nucleus together is far greater than the energy that holds electrons to a nucleus. For example, the ionization energy gained by adding an electron to a hydrogen nucleus is 13.6 electron volts — less than one-millionth of the 17 MeV released in the D-T (deuterium-tritium) reaction shown to the top right.

Building upon the nuclear transmutation experiments of Ernest Rutherford done a few years earlier, fusion of light nuclei (hydrogen isotopes) was first observed by Mark Oliphant in 1932, and the steps of the main cycle of nuclear fusion in stars were subsequently worked out by Hans Bethe throughout the remainder of that decade.

[edit] Requirements

A substantial energy barrier must be overcome before fusion can occur. At large distances two naked nuclei repel one another because of the repulsive electrostatic force between their positively charged protons. If two nuclei can be brought close enough together, however, the electrostatic barrier can be overcome by the strong nuclear force which is stronger at close distances than the electrostatic repulsion.

When a nucleon such as a proton or neutron is added to a nucleus, the strong force attracts it to other nucleons, but primarily to its immediate neighbors due to the short range of the force. The nucleons in the interior of a nucleus have more neighboring nucleons than those on the surface. Since smaller nuclei have a larger surface area-to-volume ratio, the binding energy per nucleon due to the strong force generally increases with the size of the nucleus but approaches a limiting value corresponding to that of a fully surrounded nucleon.

The electrostatic force, on the other hand, is an inverse-square force, so a proton added to a nucleus will feel an electrostatic repulsion from all the other protons in the nucleus. The electrostatic energy per nucleon due to the electrostatic force thus increases without limit as nuclei get larger.

The net result of these opposing forces is that the binding energy per nucleon generally increases with increasing size, up to the elements iron and nickel, and then decreases for heavier nuclei. Eventually, the binding energy becomes negative and very heavy nuclei are not stable. The four most tightly bound nuclei, in decreasing order of binding energy, are 62Ni, 58Fe, 56Fe, and 60Ni.[1] Even though the nickel isotope ,62Ni, is more stable, the iron isotope 56Fe is an order of magnitude more common. This is due to a greater disintegration rate for 62Ni in the interior of stars driven by photon absorption.

A notable exception to this general trend is the helium-4 nucleus, whose binding energy is higher than that of lithium, the next heavier element. The Pauli exclusion principle provides an explanation for this exceptional behavior — it says that because protons and neutrons are fermions, they cannot exist in exactly the same state. Each proton or neutron energy state in a nucleus can accommodate both a spin up particle and a spin down particle. Helium-4 has an anomalously large binding energy because its nucleus consists of two protons and two neutrons; so all four of its nucleons can be in the ground state. Any additional nucleons would have to go into higher energy states.

The situation is similar if two nuclei are brought together. As they approach each other, all the protons in one nucleus repel all the protons in the other. Not until the two nuclei actually come in contact can the strong nuclear force take over. Consequently, even when the final energy state is lower, there is a large energy barrier that must first be overcome. It is called the Coulomb barrier.

The Coulomb barrier is smallest for isotopes of hydrogen — they contain only a single positive charge in the nucleus. A bi-proton is not stable, so neutrons must also be involved, ideally in such a way that a helium nucleus, with its extremely tight binding, is one of the products.

Using deuterium-tritium fuel, the resulting energy barrier is about 0.1 MeV. In comparison, the energy needed to remove an electron from hydrogen is 13.6 eV, about 7,500 times less energy. The (intermediate) result of the fusion is an unstable 5He nucleus, which immediately ejects a neutron with 14.1 MeV. The recoil energy of the remaining 4He nucleus is 3.5 MeV, so the total energy liberated is 17.6 MeV. This is many times more than what was needed to overcome the energy barrier.

If the energy to initiate the reaction comes from accelerating one of the nuclei, the process is called beam-target fusion; if both nuclei are accelerated, it is beam-beam fusion. If the nuclei are part of a plasma near thermal equilibrium, one speaks of thermonuclear fusion. Temperature is a measure of the average kinetic energy of particles, so by heating the nuclei they will gain energy and eventually have enough to overcome this 0.1 MeV. Converting the units between electronvolts and kelvins shows that the barrier would be overcome at a temperature in excess of 1 GK, obviously a very high temperature.

There are two effects that lower the actual temperature needed. One is the fact that temperature is the average kinetic energy, implying that some nuclei at this temperature would actually have much higher energy than 0.1 MeV, while others would be much lower. It is the nuclei in the high-energy tail of the velocity distribution that account for most of the fusion reactions. The other effect is quantum tunneling. The nuclei do not actually have to have enough energy to overcome the Coulomb barrier completely. If they have nearly enough energy, they can tunnel through the remaining barrier. For this reason fuel at lower temperatures will still undergo fusion events, at a lower rate.
The deuterium-tritium fusion reaction rate increases rapidly with temperature until it maximizes near 70 keV (800 million kelvins) and then gradually drops off.
The deuterium-tritium fusion reaction rate increases rapidly with temperature until it maximizes near 70 keV (800 million kelvins) and then gradually drops off.

The reaction cross section σ is a measure of the probability of a fusion reaction as a function of the relative velocity of the two reactant nuclei. If the reactants have a distribution of velocities, e.g. a thermal distribution with thermonuclear fusion, then it is useful to perform an average over the distributions of the product of cross section and velocity. The reaction rate (fusions per volume per time) is <σv> times the product of the reactant number densities:

f = n_1 n_2 \langle \sigma v \rangle

If a species of nuclei is reacting with itself, such as the DD reaction, then the product n1n2 must be replaced by (1 / 2)n2.

\langle \sigma v \rangle increases from virtually zero at room temperatures up to meaningful magnitudes at temperatures of 10 – 100 keV. At these temperatures, well above typical ionization energies (13.6 eV in the hydrogen case), the fusion reactants exist in a plasma state.

The significance of <σv> as a function of temperature in a device with a particular energy confinement time is found by considering the Lawson criterion.

[edit] Fuel confinement methods

The fusion reaction can sustain itself if enough of the energy produced goes into keeping the fuel hot.

[edit] Gravitational

One force capable of confining the fuel well enough to satisfy the Lawson criterion is gravity. The mass needed, however, is so great that gravitational confinement is only found in stars (the smallest of which are brown dwarfs). Even if the more reactive fuel deuterium were used, a mass greater than that of the planet Jupiter would be needed.

[edit] Magnetic

See Magnetic fusion energy for more information.

Since plasmas are very good electrical conductors, magnetic fields can also confine fusion fuel. A variety of magnetic configurations can be used, the most basic distinction being between mirror confinement and toroidal confinement, especially tokamaks and stellarators.

[edit] Inertial

See Inertial fusion energy for more information.

A third confinement principle is to apply a rapid pulse of energy to a large part of the surface of a pellet of fusion fuel, causing it to simultaneously "implode" and heat to very high pressure and temperature. If the fuel is dense enough and hot enough, the fusion reaction rate will be high enough to burn a significant fraction of the fuel before it has dissipated. To achieve these extreme conditions, the initially cold fuel must be explosively compressed. Inertial confinement is used in the hydrogen bomb, where the driver is x-rays created by a fission bomb. Inertial confinement is also attempted in "controlled" nuclear fusion, where the driver is a laser, ion, or electron beam, or a Z-pinch.

Some other confinement principles have been investigated, such as muon-catalyzed fusion, the Farnsworth-Hirsch fusor (inertial electrostatic confinement), and bubble fusion.

[edit] Production methods

A variety of methods are known to effect nuclear fusion. Some are "cold" in the strict sense that no part of the material is hot (except for the reaction products), some are "cold" in the limited sense that the bulk of the material is at a relatively low temperature and pressure but the reactants are not, and some are "hot" fusion methods that create macroscopic regions of very high temperature and pressure.

[edit] Locally cold fusion

* Muon-catalyzed fusion is a well-established and reproducible fusion process that occurs at ordinary temperatures. It was studied in detail by Steven Jones in the early 1980s. It has not been reported to produce net energy. Net energy production from this reaction is not believed to be possible because of the energy required to create muons, their 2.2 µs half-life, and the chance that a muon will bind to the new alpha particle and thus stop catalyzing fusion.

[edit] Generally cold, locally hot fusion

* Accelerator based light-ion fusion. Using particle accelerators it is possible to achieve particle kinetic energies sufficient to induce many light ion fusion reactions. Of particular relevance into this discussion are devices referred to as sealed-tube neutron generators. These small devices are miniature particle accelerators filled with deuterium and tritium gas in an arrangement which allows ions of these nuclei to be accelerated against hydride targets, also containing deuterium and tritium, where fusion takes place. Hundreds of neutron generators are produced annually for use in the petroleum industry where they are used in measurement equipment for locating and mapping oil reserves. Despite periodic reports in the popular press by scientists claiming to have invented "table-top" fusion machines, neutron generators have been around for half a century. The sizes of these devices vary but the smallest instruments are often packaged in sizes smaller than a loaf of bread. These devices do not produce a net power output.

* In sonoluminescence, acoustic shock waves create temporary bubbles that collapse shortly after creation, producing very high temperatures and pressures. In 2002, Rusi P. Taleyarkhan reported the possibility that bubble fusion occurs in those collapsing bubbles (aka sono fusion). As of 2005, experiments to determine whether fusion is occurring give conflicting results. If fusion is occurring, it is because the local temperature and pressure are sufficiently high to produce hot fusion.[2]
* The Farnsworth-Hirsch Fusor is a tabletop device in which fusion occurs. This fusion comes from high effective temperatures produced by electrostatic acceleration of ions. The device can be built inexpensively, but it too is unable to produce a net power output.
* Antimatter-initialized fusion uses small amounts of antimatter to trigger a tiny fusion explosion. This has been studied primarily in the context of making nuclear pulse propulsion feasible. This is not near becoming a practical power source, due to the cost of manufacturing antimatter alone.
* Pyroelectric fusion was reported in April 2005 by a team at UCLA. The scientists used a pyroelectric crystal heated from −34 to 7°C (−30 to 45°F), combined with a tungsten needle to produce an electric field of about 25 gigavolts per meter to ionize and accelerate deuterium nuclei into an erbium deuteride target. Though the energy of the deuterium ions generated by the crystal has not been directly measured, the authors used 100 keV (a temperature of about 109 K) as an estimate in their modeling.[3] At these energy levels, two deuterium nuclei can fuse together to produce a helium-3 nucleus, a 2.45 MeV neutron and bremsstrahlung. Although it makes a useful neutron generator, the apparatus is not intended for power generation since it requires far more energy than it produces.[4][5][6][7]

[edit] Hot fusion

* "Standard" "hot" fusion, in which the fuel reaches tremendous temperature and pressure inside a fusion reactor or nuclear weapon.

The methods in the second group are examples of non-equilibrium systems, in which very high temperatures and pressures are produced in a relatively small region adjacent to material of much lower temperature. In his doctoral thesis for MIT, Todd Rider did a theoretical study of all quasineutral, isotropic, non-equilibrium fusion systems. He demonstrated that all such systems will leak energy at a rapid rate due to bremsstrahlung, radiation produced when electrons in the plasma hit other electrons or ions at a cooler temperature and suddenly decelerate. The problem is not as pronounced in a hot plasma because the range of temperatures, and thus the magnitude of the deceleration, is much lower. Note that Rider's work does not apply to non-neutral and/or anisotropic non-equilibrium plasmas.

[edit] Important reactions

[edit] Astrophysical reaction chains
The Proton-proton chain dominates in stars the size of the Sun or smaller.
The Proton-proton chain dominates in stars the size of the Sun or smaller.
The CNO cycle dominates in stars heavier than the Sun.
The CNO cycle dominates in stars heavier than the Sun.

The most important fusion process in nature is that which powers the stars. The net result is the fusion of four protons into one alpha particle, with the release of two positrons, two neutrinos (which changes two of the protons into neutrons), and energy, but several individual reactions are involved, depending on the mass of the star. For stars the size of the sun or smaller, the proton-proton chain dominates. In heavier stars, the CNO cycle is more important. Both types of processes are responsible for the creation of new elements as part of stellar nucleosynthesis.

At the temperatures and densities in stellar cores the rates of fusion reactions are still extremely slow. For example, at solar core temperature (T ~ 15 MK) and density (~120 g/cm3), the energy release rate is only ~0.1 microwatt/cm3 — millions of times less than the rate of energy release of ordinary candela and thousands of times less than the rate at which a human body generates heat. Thus, reproduction of stellar core conditions in a lab for nuclear fusion power production is completely impractical.

[edit] Criteria and candidates for terrestrial reactions

In man-made fusion, the primary fuel is not constrained to be protons and higher temperatures can be used, so reactions with larger cross-sections are chosen. This implies a lower Lawson criterion, and therefore less startup effort. Another concern is the production of neutrons, which activate the reactor structure radiologically, but also have the advantages of allowing volumetric extraction of the fusion energy and tritium breeding. Reactions that release no neutrons are referred to as aneutronic.

In order to be useful as a source of energy, a fusion reaction must satisfy several criteria. It must:

* be exothermic - This may be obvious, but it limits the reactants to the low Z (number of protons) side of the curve of binding energy. It also makes helium He-4 the most common product because of its extraordinarily tight binding, although He3 and H3 also show up
* involve low Z nuclei - This is because the electrostatic repulsion must be overcome before the nuclei are close enough to fuse
* have two reactants - At anything less than stellar densities, three body collisions are too improbable. It should be noted that in inertial confinement, both stellar densities and temperatures are exceeded to compensate for the shortcomings of the third parameter of the Lawson criterion, ICF's very short confinement time.
* have two or more products - This allows simultaneous conservation of energy and momentum without relying on the electromagnetic force
* conserve both protons and neutrons - The cross sections for the weak interaction are too small

Few reactions meet these criteria. The following are those with the largest cross sections:
(1) D + T → 4He (3.5 MeV) + n (14.1 MeV)
(2i) D + D → T (1.01 MeV) + p (3.02 MeV) 50%
(2ii) → 3He (0.82 MeV) + n (2.45 MeV) 50%
(3) D + 3He → 4He (3.6 MeV) + p (14.7 MeV)
(4) T + T → 4He + 2 n + 11.3 MeV
(5) 3He + 3He → 4He + 2 p + 12.9 MeV
(6i) 3He + T → 4He + p + n + 12.1 MeV 51%
(6ii) → 4He (4.8 MeV) + D (9.5 MeV) 43%
(6iii) → 4He (0.5 MeV) + n (1.9 MeV) + p (11.9 MeV) 6%
(7) D + 6Li → 2 4He + 22.4 MeV
(8) p + 6Li → 4He (1.7 MeV) + 3He (2.3 MeV)
(9) 3He + 6Li → 2 4He + p + 16.9 MeV
(10) p + 11B → 3 4He + 8.7 MeV

p (protium), D (deuterium), and T (tritium) are shorthand notation for the main three isotopes of hydrogen.

For reactions with two products, the energy is divided between them in inverse proportion to their masses, as shown. In most reactions with three products, the distribution of energy varies. For reactions that can result in more than one set of products, the branching ratios are given.

Some reaction candidates can be eliminated at once.[8] The D-6Li reaction has no advantage compared to p-11B because it is roughly as difficult to burn but produces substantially more neutrons through D-D side reactions. There is also a p-7Li reaction, but the cross section is far too low, except possibly when Ti > 1 MeV, but at such high temperatures an endothermic, direct neutron-producing reaction also becomes very significant. Finally there is also a p-9Be reaction, which is not only difficult to burn, but 9Be can be easily induced to split into two alphas and a neutron.

In addition to the fusion reactions, the following reactions with neutrons are important in order to "breed" tritium in "dry" fusion bombs and some proposed fusion reactors:

n + 6Li → T + 4He
n + 7Li → T + 4He + n

To evaluate the usefulness of these reactions, in addition to the reactants, the products, and the energy released, one needs to know something about the cross section. Any given fusion device will have a maximum plasma pressure that it can sustain, and an economical device will always operate near this maximum. Given this pressure, the largest fusion output is obtained when the temperature is chosen so that <σv>/T² is a maximum. This is also the temperature at which the value of the triple product nTτ required for ignition is a minimum. (A plasma is "ignited" if the fusion reactions produce enough power to maintain the temperature without external heating.) This optimum temperature and the value of <σv>/T² at that temperature is given for a few of these reactions in the following table.
fuel T [keV] <σv>/T² [m³/s/keV²]
D-T 13.6 1.24×10-24
D-D 15 1.28×10-26
D-3He 58 2.24×10-26
p-6Li 66 1.46×10-27
p-11B 123 3.01×10-27

Note that many of the reactions form chains. For instance, a reactor fueled with T and 3He will create some D, which is then possible to use in the D + 3He reaction if the energies are "right". An elegant idea is to combine the reactions (8) and (9). The 3He from reaction (8) can react with 6Li in reaction (9) before completely thermalizing. This produces an energetic proton which in turn undergoes reaction (8) before thermalizing. A detailed analysis shows that this idea will not really work well, but it is a good example of a case where the usual assumption of a Maxwellian plasma is not appropriate.

[edit] Neutronicity, confinement requirement, and power density
The only fusion reactions thus far produced by humans to achieve ignition are those which have been created in hydrogen bombs; the first of which, shot Ivy Mike, is shown here.
The only fusion reactions thus far produced by humans to achieve ignition are those which have been created in hydrogen bombs; the first of which, shot Ivy Mike, is shown here.

Any of the reactions above can in principle be the basis of fusion power production. In addition to the temperature and cross section discussed above, we must consider the total energy of the fusion products Efus, the energy of the charged fusion products Ech, and the atomic number Z of the non-hydrogenic reactant.

Specification of the D-D reaction entails some difficulties, though. To begin with, one must average over the two branches (2) and (3). More difficult is to decide how to treat the T and 3He products. T burns so well in a deuterium plasma that it is almost impossible to extract from the plasma. The D-3He reaction is optimized at a much higher temperature, so the burnup at the optimum D-D temperature may be low, so it seems reasonable to assume the T but not the 3He gets burned up and adds its energy to the net reaction. Thus we will count the DD fusion energy as Efus = (4.03+17.6+3.27)/2 = 12.5 MeV and the energy in charged particles as Ech = (4.03+3.5+0.82)/2 = 4.2 MeV.

Another unique aspect of the D-D reaction is that there is only one reactant, which must be taken into account when calculating the reaction rate.

With this choice, we tabulate parameters for four of the most important reactions.
fuel Z Efus [MeV] Ech [MeV] neutronicity
D-T 1 17.6 3.5 0.80
D-D 1 12.5 4.2 0.66
D-3He 2 18.3 18.3 ~0.05
p-11B 5 8.7 8.7 ~0.001

The last column is the neutronicity of the reaction, the fraction of the fusion energy released as neutrons. This is an important indicator of the magnitude of the problems associated with neutrons like radiation damage, biological shielding, remote handling, and safety. For the first two reactions it is calculated as (Efus-Ech)/Efus. For the last two reactions, where this calculation would give zero, the values quoted are rough estimates based on side reactions that produce neutrons in a plasma in thermal equilibrium.

Of course, the reactants should also be mixed in the optimal proportions. This is the case when each reactant ion plus its associated electrons accounts for half the pressure. Assuming that the total pressure is fixed, this means that density of the non-hydrogenic ion is smaller than that of the hydrogenic ion by a factor 2/(Z+1). Therefore the rate for these reactions is reduced by the same factor, on top of any differences in the values of <σv>/T². On the other hand, because the D-D reaction has only one reactant, the rate is twice as high as if the fuel were divided between two hydrogenic species.

Thus there is a "penalty" of (2/(Z+1)) for non-hydrogenic fuels arising from the fact that they require more electrons, which take up pressure without participating in the fusion reaction. (It is usually a good assumption that the electron temperature will be nearly equal to the ion temperature. Some authors, however discuss the possibility that the electrons could be maintained substantially colder than the ions. In such a case, known as a "hot ion mode", the "penalty" would not apply.) There is at the same time a "bonus" of a factor 2 for D-D due to the fact that each ion can react with any of the other ions, not just a fraction of them.

We can now compare these reactions in the following table.
fuel <σv>/T² penalty/bonus reactivity Lawson criterion power density
D-T 1.24×10-24 1 1 1 1
D-D 1.28×10-26 2 48 30 68
D-3He 2.24×10-26 2/3 83 16 80
p-11B 3.01×10-27 1/3 1240 500 2500

The maximum value of <σv>/T2 is taken from a previous table. The "penalty/bonus" factor is that related to a non-hydrogenic reactant or a single-species reaction. The values in the column "reactivity" are found by dividing 1.24×10-24 by the product of the second and third columns. It indicates the factor by which the other reactions occur more slowly than the D-T reaction under comparable conditions. The column "Lawson criterion" weights these results with Ech and gives an indication of how much more difficult it is to achieve ignition with these reactions, relative to the difficulty for the D-T reaction. The last column is labeled "power density" and weights the practical reactivity with Efus. It indicates how much lower the fusion power density of the other reactions is compared to the D-T reaction and can be considered a measure of the economic potential.

[edit] Bremsstrahlung losses in quasineutral, isotropic plasmas

The ions undergoing fusion in many systems will essentially never occur alone but will be mixed with electrons that neutralize the ions' electrical charge and form a plasma. The electrons will generally have a temperature comparable to or greater than that of the ions, so they will collide with the ions and emit Bremsstrahlung. The Sun and stars are opaque to Bremsstrahlung, but essentially any terrestrial fusion reactor will be optically thin at relevant wavelengths. Bremsstrahlung is also difficult to reflect and difficult to convert directly to electricity, so the ratio of fusion power produced to Bremsstrahlung radiation lost is an important figure of merit. This ratio is generally maximized at a much higher temperature than that which maximizes the power density (see the previous subsection). The following table shows the rough optimum temperature and the power ratio at that temperature for several reactions.[9]
fuel Ti (keV) Pfusion/PBremsstrahlung
D-T 50 140
D-D 500 2.9
D-3He 100 5.3
3He-3He 1000 0.72
p-6Li 800 0.21
p-11B 300 0.57

The actual ratios of fusion to Bremsstrahlung power will likely be significantly lower for several reasons. For one, the calculation assumes that the energy of the fusion products is transmitted completely to the fuel ions, which then lose energy to the electrons by collisions, which in turn lose energy by Bremsstrahlung. However because the fusion products move much faster than the fuel ions, they will give up a significant fraction of their energy directly to the electrons. Secondly, the plasma is assumed to be composed purely of fuel ions. In practice, there will be a significant proportion of impurity ions, which will lower the ratio. In particular, the fusion products themselves must remain in the plasma until they have given up their energy, and will remain some time after that in any proposed confinement scheme. Finally, all channels of energy loss other than Bremsstrahlung have been neglected. The last two factors are related. On theoretical and experimental grounds, particle and energy confinement seem to be closely related. In a confinement scheme that does a good job of retaining energy, fusion products will build up. If the fusion products are efficiently ejected, then energy confinement will be poor, too.

The temperatures maximizing the fusion power compared to the Bremsstrahlung are in every case higher than the temperature that maximizes the power density and minimizes the required value of the fusion triple product. This will not change the optimum operating point for D-T very much because the Bremsstrahlung fraction is low, but it will push the other fuels into regimes where the power density relative to D-T is even lower and the required confinement even more difficult to achieve. For D-D and D-3He, Bremsstrahlung losses will be a serious, possibly prohibitive problem. For 3He-3He, p-6Li and p-11B the Bremsstrahlung losses appear to make a fusion reactor using these fuels with a quasineutral, anisotropic plasma impossible. Some ways out of this dilemma are considered — and rejected — in Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium by Todd Rider.[10] This limitation does not apply to non-neutral and anisotropic plasmas; however, these have their own challenges to contend with.

world war 2

War in Europe

Main article: European Theatre of World War II

WW II Europe.

On September 1, 1939, Germany, led by Adolf Hitler and the Nazi Party, invaded Poland according to a secret agreement with the Soviet Union.

On September 3 at 11.15 GMT, the United Kingdom, Australia and New Zealand, followed six hours later by France, responded by declaring war on Germany, initiating a widespread naval war. South Africa (September 6) and Canada (September 10) followed suit.

The Soviet Union joined the invasion of Poland on September 17.

Germany rapidly overwhelmed Poland, then Norway, the Netherlands, Belgium and France in 1940, and Yugoslavia and Greece in 1941. Italian, and later German, troops attacked British forces in North Africa. By summer of 1941, Germany had conquered France and most of Western Europe, but it failed to subdue the United Kingdom due to the resistance of the Royal Air Force and Royal Navy.

Adolf Hitler then turned on the Soviet Union, launching a surprise attack (codenamed Operation Barbarossa) on June 22, 1941. Despite enormous gains, the invasion bogged down outside of Moscow in late 1941 as winter set in and made further advances difficult. The Germans launched another attack in the Soviet Union the following summer, but the attack bogged down in vicious urban fighting in Stalingrad. The Soviets later launched a massive counterattack encircling and then forcing the surrender of the German Sixth Army at the Battle of Stalingrad (1942–43), decisively defeated the Axis during the Battle of Kursk, and broke the Siege of Leningrad. The Red Army then pursued the retreating Wehrmacht all the way to Berlin, and won the street-by-street Battle of Berlin, as Hitler committed suicide in his Underground Bunker on April 30, 1945.

Meanwhile, the Western Allies successfully defended North Africa (1940–43), invaded Italy (1943), and then liberated France (1944), following amphibious landings in Normandy. Repulsing a German counterattack at the Battle of the Bulge in December, the Western Allies crossed the Rhine and linked up with their Soviet counterparts at the Elbe in central Germany.

During the war in Europe, six million Jews, as well as another five to six million Roma (Gypsies), Slavs, Communists, homosexuals, the disabled and several other groups, were murdered by Germany in a state-sponsored genocide that has come to be known as The Holocaust.

War in Asia and the Pacific

Main article: Pacific War

Territory of the Empire of Japan at its peak
Territory of the Empire of Japan at its peak

The Empire of Japan invaded China on July 7, 1937. Australia and then the United States, in 1940, responded with embargos on the export of iron to Japan. On September 27, 1940 Japan signed the Tripartite Pact with Germany and Italy. After unfruitful negotiations with USA about withdrawal from China, excluding Manchukuo, Japan attacked Vichy French-controlled Indochina on July 24, 1941. This caused the United States, United Kingdom and Netherlands to block Japan's access to oil, such as that in the Dutch East Indies and British colonies in Borneo.

Japan launched virtually simultaneous surprise attacks against the major U. S. Navy base at Pearl Harbor, on Thailand and on the British territories of Malaya and Hong Kong. These attacks were on December 7, 1941 in western international time zones and on December 8 in the east. Later on December 8, Japan attacked The Philippines, which was controlled politically by the U.S. at the time and quickly fell to Japanese forces. On December 11, Germany and Italy also declared war on the United States. Japanese forces began their assaults on British and Dutch territory in Borneo on December 15. From their major pre-war base at Truk, in the South Pacific, Japanese forces began to attack and occupy neighboring Allied territories.

Japan's campaign in China lasted from 1937 to the end of the war, during which the Republic of China faced 80% of Japanese troops and prevented the Soviet Union under Stalin from fighting a two-fronts-war. During its occupation of some parts of China, the Japanese killed over 11 million civilians.

Japan won victory after victory in South East Asia and the Pacific, including the capture of 130,000 Allied prisoners in Malaya and at the fall of Singapore on February 15, 1942. Much of Burma, the Netherlands East Indies, the Australian Territory of New Guinea, and the British Solomon Islands also fell to Japanese forces.

The Japanese advance was checked at the Battle of the Coral Sea and their invasion fleet turned away from New Guinea after Allied naval forces clashed in the first battle in which the opposing fleets never made visual contact. A month later a Japanese invasion fleet was decisively defeated at the Battle of Midway in which they lost four fleet aircraft carriers attempting to engage U.S. Navy forces (the U.S. Navy lost one carrier). On land they were defeated at the Battle of Milne Bay and finally withdrew from Battle of Guadalcanal as the Allies took the initiative in the Solomon Islands and began an "Island Hopping" campaign to push back Japanese holdings in the Pacific. U.S. and Australian forces then isolated Japan's major base at Rabaul before advancing from one island to another in the Central Pacific invading some and isolating others. The Japanese were defeated in a series of great naval battles, at the Battle of the Philippine Sea and the Battle of Leyte Gulf in 1944 in which the Allies further advanced towards the Japanese homeland by invading the Marianas and then the Philippines, setting up bases from which Japan could be bombed by strategic bombers like the B-29. 1945 saw invasions of key islands such as Iwo Jima and Okinawa. In the meantime, Allied submarines gradually cut off the supply of oil and other raw materials to Japan.

In the last year of the war U.S. air forces conducted a strategic firebombing campaign against the Japanese homeland. On August 6, 1945, the U.S. dropped an atomic bomb on the Japanese city of Hiroshima, and on August 9 another was dropped on Nagasaki. Japan surrendered on August 14, 1945.

Aftermath

About 62 million people, or 2.5% of the world population, died in the war, though estimates vary greatly (see World War II casualties). Large swaths of Europe and Asia were devastated and took years to recover. The war had political, sociological, economic and technological consequences that last to this day.

Causes
Benito Mussolini of Fascist Italy (left) and Adolf Hitler of Nazi Germany.
Benito Mussolini of Fascist Italy (left) and Adolf Hitler of Nazi Germany.

Main articles: Causes of World War II, Events preceding World War II in Europe, and Events preceding World War II in Asia

The immediate causes of World War II are generally held to be the German invasion of Poland, and the Japanese attacks on China, the United States, and the British and Dutch colonies. In each of these cases, the attacks were the result of a decision made by authoritarian ruling elites in Germany and Japan. World War II started after these aggressive actions were met with an official declaration of war, armed resistance or both.

The chief stated aim of the German policy at the time was the reacquisition of German territories taken by the Treaty of Versailles, and the addition of ethnic German regions of former Austria-Hungary to form a Greater Germany.

Cause of war in Europe

German foreign policy professed concern for the rights of ethnic Germans living in portions of Poland and Czechoslovakia which had been taken from Germany and Austria respectively. During his negotiations with Chamberlain, Hitler mentioned their plight as one of his key reasons for asserting claims to portions of these countries.

During one session with UK Prime Minister Neville Chamberlain, Hitler's aides brought him multiple reports alleging atrocities against ethnic Germans in nearby countries, which Hitler invoked in support of Germany's claims to its former territory.
Molotov signs the Molotov-Ribbentrop Pact in Moscow. Behind him are Shaposhnikov, Ribbentrop, and Stalin.
Molotov signs the Molotov-Ribbentrop Pact in Moscow. Behind him are Shaposhnikov, Ribbentrop, and Stalin.

When Hitler annexed parts of Czechoslovakia and France, he was welcomed enthusiastically by these ethnic Germans. When the war ended, many of these communities were forcibly expelled.[1]

Another of the main reasons that German society moved towards war was due to the perceived inequities of the Versailles Treaty. (More than anything else, this treaty, coupled with the worldwide Great Depression of the 1930s, enabled the Nazis to originally ride a wave of mass public discontent to power, and to set in place their fascist forms of dictatorship and re-militarization.) The Nazis claimed that only they could free Germany from international subjugation. Hitler remilitarized the Rhineland and the Ruhr, and overturned several territorial dispositions which were enacted by the treaty.

As stated in Mein Kampf, Hitler's real underlying goal was to acquire what he believed to be Germany's rightful living space and resources, by invading and dominating lands to the east, mainly in Russia. He also sought to attack various ethnic and political groups, to target what he claimed were leftist influences, and other groups outside of the Nazi world-view. By starting with the real grievances of the Versailles Treaty, the Nazis were able to stoke a sense of grievance throughout Germany to redress perceived wrongs, and to present militarism and adherence to fascism as a means of taking aggressive action against the established political order.

In the hands of the Nazis, this issue is used to rationalize brutal persecution of entire ethnic minorities and political groups. This effort against existing international settlements enabled a convergence of their political programs, war aims, and racist ideologies.

The British and French governments followed a policy of appeasement in order to avoid a new European war. This was partially due to doubts about the willingness of their populations to fight another war so soon after the huge death tolls of the first World War. This policy culminated in the Munich Agreement in 1938, in which the seemingly inevitable outbreak of the war was averted when the United Kingdom and France agreed to Germany's annexation and immediate occupation of the German-speaking regions of Czechoslovakia. Chamberlain declared that the agreement represented "peace in our time". In March 1939, Germany invaded the rest of Czechoslovakia, effectively killing appeasement. Less than a year after the Munich agreement, the United Kingdom and France declared war on Germany.
Hideki Tojo of Imperial Japan
Hideki Tojo of Imperial Japan

The failure of the Munich Agreement showed that deals made with Hitler at the negotiating table could not be trusted and that his aspirations for power and dominance in Europe went beyond anything that the United Kingdom and France would tolerate. Poland and France pledged on May 19, 1939, to provide each other with military assistance in the event either was attacked. The British had already offered support to Poland in March. On August 23, 1939, Germany and the Soviet Union signed the Molotov-Ribbentrop Pact. The Pact included a secret protocol that would divide Central Europe into German and Soviet areas of interest, including a provision to partition Poland. Each country agreed to allow the other a free hand in its area of influence, including military occupation. The deal provided for sales of oil and food from the Soviets to Germany, thus reducing the danger of a UK blockade such as the one that had nearly starved Germany in World War I. Hitler was then ready to go to war with Poland and, if necessary, with the United Kingdom and France. He claimed there were German grievances relating to the issues of the Free City of Danzig and the Polish Corridor, but he planned to conquer all Polish territory and incorporate it into the German Reich. The signing of a new alliance between the United Kingdom and Poland on August 25 did not significantly alter his plans.

Cause of war in Asia

Imperial Japan in the 1930s was largely ruled by a militarist clique of Army and Navy leaders, who aimed to make Japan a great colonial power. Japan invaded Manchuria in 1931 and China in 1937 to bolster its meager stock of natural resources, to relieve Japan from population pressures and to extend its colonial control over a wider area. The United States and the United Kingdom reacted by making loans to China, providing covert military assistance, pilots and fighter aircraft to Kuomintang China and instituting increasingly broad embargoes of raw materials and oil against Japan. These embargoes would potentially have eventually forced Japan to give up its newly conquered possessions in China or find new sources of oil and other materials to run their economy. Japan was faced with the choice of withdrawing from China, negotiating some compromise, developing new sources of supply, buying what they needed somewhere else, or going to war to conquer the territories that contained oil, bauxite and other resources in the Dutch East Indies, Malay and the Philippines. Believing the French, Dutch and British governments more than occupied with the war in Europe, the Soviets reeling from German attacks and that the United States could not be organized for war for years and would seek a compromise before waging full scale war, they chose the latter, and went ahead with plans for the Greater East Asia War in the Pacific.[2]

The direct cause of the United States' entry into the war with Japan was the attack on Pearl Harbor on December 7, 1941. Germany declared war on the United States on December 11, 1941.

Chronology

Main article: Timeline of World War II

War breaks out in Asia (July 1937 – September 1939)

Main articles: Second Sino-Japanese War, Battle of Lake Khasan, and Battle of Khalkhin Gol

The Second Sino-Japanese War began in 1937, when Japan attacked deep into China from its foothold in Manchuria. On July 7, 1937, Japan, after occupying Manchuria since 1931, launched another attack against China near Beijing. The Japanese made initial advances but were stalled in the Battle of Shanghai. The city eventually fell to the Japanese in December 1937, and the capital city Nanjing also fell. As a result, the Chinese Nationalist government moved its seat to Chongqing for the remainder of the war. The Japanese forces committed brutal atrocities against civilians and prisoners of war in the Rape of Nanking, slaughtering as many as 300,000 civilians within a month. Neither Japan or China officially declared war, for a similar reason—fearing declaration of war would alienate Europe and the USA.

In Spring 1939, Soviet and Japanese forces clashed in Mongolia. On May 8, 700 Mongol horsemen crossed the Khalka river, which the Japanese considered to be the Manchurian border. The Soviet and Mongolian governments believed the border was twenty miles to the east. Mongol and Manchu forces began to shoot at each other, and within days their Soviet and Japanese patrons had sent large military contingents, which almost immediately joined in the clash, which led to a full-scale war which lasted well into September. The growing Japanese presence in the Far East was seen as a major strategic threat by the Soviet Union, and Soviet fear of having to fight a two front war was a primary reason for the Molotov-Ribbentrop Pact with the Nazis. In the end, the Japanese were decisively defeated by Soviet units under General Georgiy Zhukov. Following this battle, the Soviet Union and Japan were at peace until 1945. Japan looked south to expand its empire, leading to conflict with the United States over the Philippines and control of shipping lanes to the Dutch East Indies. The Soviet Union focused on the west, leaving only minimal troops to guard the frontier with Japan.

War breaks out in Europe (September 1939 – May 1940)

Main articles: Invasion of Poland (1939), Winter War, and Occupation of Baltic Republics

Polish infantry during the Invasion of Poland, September 1939.
Polish infantry during the Invasion of Poland, September 1939.

On September 1, 1939, Germany invaded Poland, using the false pretext of a faked "Polish attack" on a German border post. The United Kingdom and France gave Germany two days to withdraw from Poland. Once the deadline passed on September 3, the United Kingdom, Australia, and New Zealand declared war on Germany, followed quickly by France, South Africa and Canada.

The French mobilized slowly and then mounted only a token offensive in the Saar, which they soon abandoned, while the British could not take any direct action in support of the Poles in the time available (see Western betrayal). Meanwhile, on September 8, the Germans reached Warsaw, having slashed through the Polish defenses.

On September 17, the Soviet Union, pursuant to its secret agreement with Germany, invaded Poland from the east, throwing Polish defenses into chaos by opening the second front. A day later, both the Polish president and commander-in-chief fled to Romania. On October 1, hostile forces, after a one-month siege of Warsaw, entered the city. The last Polish units surrendered on October 6. Poland, however, never officially surrendered to the Germans. Some Polish troops evacuated to neighboring countries. In the aftermath of the September Campaign, occupied Poland managed to create a powerful resistance movement and contributed significant military forces to the Allies for the duration of World War II.

After Poland fell, Germany paused to regroup during the winter of 1939–1940 until April 1940, while the British and French stayed on the defensive. The period was referred to by journalists as “the Phony War” or the “Sitzkrieg” because so little ground combat took place. During this period Soviet Union attacked Finland on November 30, 1939, which started the Winter War. Despite outnumbering Finnish troops by 4 to 1, the Red Army found the attack embarrassingly difficult, and the Finnish defence prevented an all-out invasion. Finally, however, the Soviets prevailed and the peace treaty saw Finland cede strategically important border areas near Leningrad.

Germany invaded Denmark and Norway on April 9, 1940, in Operation Weserübung, in part to counter the threat of an impending Allied invasion of Norway. Denmark did not resist, but Norway fought back. The United Kingdom, whose own invasion was ready to launch, landed in the north. By late June, the Allies were defeated and withdrew, Germany controlled most of Norway, and the Norwegian Army had surrendered, while the Norwegian Royal Family escaped to London. Germany used Norway as a base for air and naval attacks on Arctic convoys headed to the Soviet Union. Norwegian partisans would continue to fight against the German occupation throughout the war.

The Western Front (May 1940 – September 1940)

Main articles: Battle of France and Battle of Britain

The Germans ended the Phony War on May 10, 1940 when they invaded Luxembourg, Belgium, the Netherlands, and France. The Netherlands was quickly overwhelmed and the Dutch city of Rotterdam was destroyed in a bombing raid. The British Expeditionary Force (BEF) and the French Army advanced into northern Belgium and planned to fight a mobile war in the north, while maintaining a static continuous front along the Maginot Line further south. The Allied plans were immediately smashed by the most classic example in history of Blitzkrieg.

In the first phase of the invasion, Fall Gelb, the Wehrmacht's Panzergruppe von Kleist, raced through the Ardennes, a heavily forested region which the Allies had thought impenetrable for a modern, mechanized army. The Germans broke the French line at Sedan, held by reservists rather than first-line troops, then drove west across northern France to the English Channel, splitting the Allies in two.

The BEF and French forces, encircled in the north, were evacuated from Dunkirk in Operation Dynamo. The operation was one of the biggest military evacuations in history, as 338,000 British and French troops were transported across the English Channel on warships and civilian boats.
Germans parading in the deserted Champs-Élysées avenue, Paris, June 1940.
Germans parading in the deserted Champs-Élysées avenue, Paris, June 1940.

On June 10, Italy joined the war, attacking France in the south. German forces then continued the conquest of France with Fall Rot (Case Red). France signed an armistice with Germany on June 22, 1940, leading to the direct German occupation of Paris and two-thirds of France, and the establishment of a German puppet state headquartered in southeastern France known as Vichy France.
Heinkel He 111 bomber over London on 7 Sep. 1940
Heinkel He 111 bomber over London on 7 Sep. 1940

Germany had begun preparations in the summer of 1940 to invade the United Kingdom in Operation Sea Lion. Most of the UK Army's heavy weapons and supplies had been lost at Dunkirk. The Germans had no hope of overpowering the Royal Navy, but they did think they had a chance of success, if they could gain air superiority. To do that, they first had to deal with the Royal Air Force (RAF). The ensuing contest in the late Summer of 1940 between the two air forces became known as the Battle of Britain. The Luftwaffe initially targeted RAF Fighter Command aerodromes and radar stations. Hitler, angered by retaliatory UK bombing raids on Berlin, switched his attentions towards the bombing of London, in an operation known as The Blitz. The Luftwaffe was eventually beaten back by Hurricanes and Spitfires, while the Royal Navy remained in control of the English Channel. Thus, the invasion plans were postponed indefinitely.

After France had fallen in 1940, the United Kingdom was out of money. Franklin Roosevelt persuaded the U.S. Congress to pass the Lend-Lease act on March 11, 1941, which provided the United Kingdom and 37 other countries with US$50 billion dollars in military equipment and other supplies, US$31.4 billion of it going to the United Kingdom and the Commonwealth. Canada operated a similar program that sent $4.7 billion in supplies to the United Kingdom.

Mediterranean (April 1940 – May 1943)

Main articles: Balkan Campaign, Battle of the Mediterranean, and North African campaign

Afrika Korps tanks advance during the North African campaign.
Afrika Korps tanks advance during the North African campaign.

Control of Southern Europe, the Mediterranean Sea and North Africa was important because the British Empire depended on shipping through the Suez Canal. If the canal fell into Axis hands or if the Royal Navy lost control of the Mediterranean, then transport between the United Kingdom, India, and Australia would have to go around the Cape of Good Hope, an increase of several thousand miles.

Following the French surrender, the British attacked the French Navy anchored in North Africa in July 1940, out of fear that it might fall into German hands. This contributed to a souring of British-French relations for the next few years. With the French fleet destroyed, the Royal Navy battled the Italian fleet for supremacy in the Mediterranean from their strong bases at Gibraltar, Malta, and Alexandria, Egypt. In Africa, Italian troops invaded and captured British Somaliland in August.

Italy invaded Greece on October 28, 1940, from Italian occupied Albania, but was quickly repulsed. By mid-December, the Greek army advanced into southern Albania, tying down 530,000 Italian troops. Meanwhile, in fulfillment of Britain's guarantee to Greece the Royal Navy struck the Italian fleet on November 11, 1940. Torpedo bombers from British aircraft carriers attacked the Italian fleet in the southern port of Taranto. One battleship was sunk and several other ships were put temporarily out of action. The success of aerial torpedoes at Taranto was noted with interest by Japan's naval chief, Yamamoto, who was considering ways of neutralizing the U.S. Pacific Fleet. Mainland Greece eventually fell to a German invasion from the East, through Bulgaria.
Field Marshal Bernard Law Montgomery, Commander of the British 8th Army
Field Marshal Bernard Law Montgomery, Commander of the British 8th Army

Italian troops crossed into Egypt from Libya to attack British forces based there in September 1940 and thus beginning the North African Campaign. The aim was to capture the Suez Canal. UK, Indian, and Australian forces Counterattacked in Operation Compass, but this offensive stopped in 1941 when much of the Australian and New Zealand (ANZAC) forces were transferred to Greece to defend it from German attack. German forces (known later as the Afrika Korps) under General Erwin Rommel, however, landed in Libya in February 1941 and renewed the assault on Egypt.

Germany also invaded Crete, which was a significant action because of the large scale use of German paratroopers. Crete was defended by about 11,000 Greek and 28,000 ANZAC troops, who had just escaped Greece without their artillery or vehicles. The Germans attacked the three main airfields of the island of Maleme, Rethimnon, and Heraklion. After one day of fighting, none of the objectives were reached and the Germans had suffered appalling casualties. German plans were in disarray and the German commander, General Kurt Student, was contemplating suicide. During the next day, through miscommunication and failure of Allied commanders to grasp the situation, Maleme airfield in western Crete fell to the Germans. The loss of Maleme enabled the Germans to fly in heavy reinforcements and overwhelm the Allied forces on the island. In light of the heavy casualties suffered by the parachutists, however, Hitler forbade further airborne operations.

In North Africa, Rommel's forces advanced rapidly eastward, laying siege to the vital seaport of Tobruk. Two Allied attempts to relieve Tobruk were defeated, but a larger offensive at the end of the year (Operation Crusader) drove Rommel back after heavy fighting.

The war between the Allied and Italian navies swung decisively in favor of the Allies on March 28, 1941, when Admiral Cunningham's ships encountered the main Italian fleet south of Cape Matapan, at the southern extremity of the Greek mainland. At the cost of a couple of aircraft shot down, the Allies sank five Italian cruisers and three destroyers, and damaged the modern battleship Vittorio Veneto. The Italian Navy was emasculated as a fighting force, and the Allied task of moving troops across the Mediterranean to Greece was eased.

In April-May 1941, there was a short war in Iraq that resulted in a renewal of UK occupation. In June, Allied forces invaded Syria and Lebanon, and captured Damascus on June 17. Later, in August, UK and Red Army troops occupied neutral Iran, securing its oil and a southern supply line to the Soviet Union.
British Infantry advance at the Second Battle of El Alamein
British Infantry advance at the Second Battle of El Alamein

At the beginning of 1942, the Allied forces in North Africa were weakened by detachments to the Far East. Rommel once again attacked and recaptured Benghazi. Then, he defeated the Allies at the Battle of Gazala, and captured Tobruk along with several thousand prisoners and large quantities of supplies. Following up, he drove deep into Egypt.

The First Battle of El Alamein took place in July 1942. Allied forces had retreated to the last defensible point before Alexandria and the Suez Canal. The Afrika Korps, however, had outrun its supplies, and the defenders stopped its thrusts. The Second Battle of El Alamein occurred between October 23 and November 3. Lieutenant-General Bernard Montgomery was in command of Allied forces known as the Eighth Army. The Allies took the offensive and, despite initially stiff German resistance, were ultimately triumphant. After the German defeat at El Alamein, the Axis forces made a successful strategic withdrawal to Tunisia.

Operation Torch was launched by the U.S., British and Free French forces on November 8, 1942. It aimed to gain control of North Africa through simultaneous landings at Casablanca, Oran, and Algiers, followed a few days later with a landing at Bône, the gateway to Tunisia. The local forces of Vichy France put up minimal resistance before submitting to the authority of Free French General Henri Giraud. In retaliation, Hitler invaded and occupied Vichy France. The German and Italian forces in Tunisia were caught in the pincers of Allied advances from Algeria in the west and Libya in the east. Rommel's tactical victory against inexperienced American forces at the Battle of the Kasserine Pass only postponed the eventual surrender of the Axis forces in North Africa in May 1943.

The Eastern Front (April 1941 – February 1943)

Main articles: Eastern Front (World War II), Invasion of Yugoslavia, Operation Barbarossa, Battle of Moscow, and Battle of Stalingrad

On April 6, 1941, German, Italian, Hungarian, and Bulgarian forces invaded Yugoslavia, ending with the surrender of the Yugoslav army on April 17, and the creation of a puppet state in Croatia. Two rival resistance movements endured in Yugoslavia for the remainder of the war. The Communist group, AVNOJ, led by Tito finally prevailed over the Chetniks led by Draža Mihailović. Also on April 6, Germany invaded Greece from Bulgaria. The Greek army was outnumbered and collapsed. Athens fell on April 27, yet the United Kingdom managed to evacuate over 50,000 troops. The stubborn Greek resistance and the attack on Yugoslavia, however, delayed the German invasion of the Soviet Union by a critical six weeks.
The eastern front at the time of the Battle of Moscow: ██ Initial Wehrmacht advance - to 9 July 1941 ██ Subsequent advances - to 1 September 1941 ██ Encirclement and battle of Kiev - to 9 September 1941 ██ Final Wehrmacht advance - to 5 December 1941
The eastern front at the time of the Battle of Moscow: ██ Initial Wehrmacht advance - to 9 July 1941 ██ Subsequent advances - to 1 September 1941 ██ Encirclement and battle of Kiev - to 9 September 1941 ██ Final Wehrmacht advance - to 5 December 1941

Three German Army Groups along with various other Axis military units who in total numbered over 3.5 million men launched the invasion of the Soviet Union on June 22, 1941. Army Group North was deployed in East Prussia and was composed of 18th and 16th infantry armies and a Panzer Army, the 4th. Its main objective was to secure the Baltic states and seize Leningrad. Opposite Army Group North were 2 Soviet Armies. The Germans threw their 600 Tanks at the junction of the two Soviet Armies in that sector. The 4th Panzer Army's objective was to cross the River Neman and River Dvina which were the two largest obstacles in route to Leningrad. On the first day, the Tanks crossed River Neman and penetrated 50 miles. Near Rasienai, the Panzers were counterattacked by 300 Soviet Tanks. It took 4 Days for the Germans to en-circle and destroy the Soviet Tanks. The Panzers then crossed the River Dvina near Dvinsk. The Germans were now in striking distance of Leningrad however Hitler ordered the Panzers to hold their position while the Infantry Armies catch up. The orders to hold would last over a week giving plenty of time to the Russians to shore up defenses around Leningrad.

Army Group Center was deployed in Poland and was composed of 9th and 4th Army and two Panzer Armies, the 3rd and 2nd. Its main objective was to capture Moscow. Opposite Army Group Center were 4 Soviet Armies. The Russians occupied a salient which jutted into German territory with its center at Bialystok. Beyond, Bialystok was Minsk which was a key railway junction. 3rd Panzer Army punched through the junction of the two Soviet Armies and crossed the River Neman and 2nd Panzer Army crossed the River Bug. While the Panzers attacked the Infantry armies struck at the Salient and encircling Russian troops at Bialystok. The Panzer's objectives was to meet at Minsk and prevent any Russian withdrawal. On June 27, 2nd and 3rd Panzer Armies met up at Minsk advancing 200 miles into Soviet Territory. In the vast pocket between Minsk and the Polish border, 32 Soviet Infantry and 8 Tank Divisions were encircled and were mercilessly attacked. 290,000 Russian soldiers were captured but 250,000 Russians managed to escape.

Army Group South was deployed in Southern Poland and Romania and was composed of 6th, 11th, and 17th armies and a Panzer Army, the 1st along with two Romanian Armies and several Italian, Slovakian and Hungarian Divisions. Its objective was to secure the oil fields of the Caucasus. In the South, the Russian Commanders had quickly reacted to the German attack and whose Tank forces vastly outnumbered the Germans. Opposite the Germans in the South were 3 Soviet Armies. The German struck at the junctions of the 3 Soviet Armies but 1st Panzer Army struck right through the Soviet Army with the objective of capturing Brody. On June 26, 5 Soviet Mechanized Corps with over 1,000 Tanks mounted a massive counterattack on 1st Panzer Army. The Battle was among the fiercest of the invasion lasting over 4 days. In the end the Germans prevailed but the Russians inflicted heavy losses on the 1st Panzer Army. With the failure of the Soviet Armored offensive, the last substantial Soviet tank forces in the south were now spent.

On July 3, Hitler finally gave the go-ahead for the Panzers to resume their drive east after the infantry armies had caught up. The next objective of Army Group Center was the city of Smolensk which commanded the road to Moscow. Facing the Germans was an old Russian defensive line where the Soviets had deployed 6 Armies. On July 6, the Soviets launched an attack with 700 Tanks against the 3rd Panzer Army. The Germans, using their overwhelming air superiority, wiped out the Soviet tanks. The 2nd Panzer Army crossed the River Dneiper and closed on Smolensk from the south while 3rd Panzer Army after defeating the Soviet counter attack approached Smolensk from the North. Trapped between their pincers were 3 Soviet Armies. On July 26, the Panzers closed the gap and then began to eliminate the pocket which yielded over 300,000 Russian prisoners but 200,000 evaded capture. Hitler by now had lost faith in battles of encirclement and wanted to defeat the Soviets by inflicting severe economic damage which meant seizing the oil fields in the south and Leningrad in the North. Tanks from Army Group Center were diverted to Army Group North and South to aid them. Hitler's generals vehemently opposed this as Moscow was only 200 miles away from Army Group Center. 4th Panzer Army after being reinforced by tanks from Army Group Center broke through the Soviet defenses on August 8 and by the end of August was only 30 miles from Leningrad. Meanwhile the Finns had pushed South East on both sides of Lake Ladoga reaching the old Finnish Soviet frontier. On September 9, Army Group North was only 7 miles from Leningrad but Hitler ordered Leningrad to besieged. The Russians mounted attacks against Army Group Center but lacking its tanks, it was in no position to go on the offensive. Hitler changed his mind and decided that tanks will be send back to Army Group Center for its all out drive on Moscow.
The October Revolution military parade on November 7, 1941, in Red Square was not cancelled despite German troops on the outskirts of Moscow.
The October Revolution military parade on November 7, 1941, in Red Square was not cancelled despite German troops on the outskirts of Moscow.

In the South by mid-July below the Pinsk Marshes, the Germans had reached to a few miles of Kiev. The 1st Panzer Army then went South while the German 17th Army struck east and in between the Germans trapped 3 Soviet Armies near Uman. As the Germans eliminated the pocket, the tanks turned north and crossed the Dneiper meanwhile 2nd Panzer Army diverted from Army Group Center had crossed the River Desna with 2nd Army on its right flank. The two Panzer armies now trapped 4 Soviet Armies and parts of two others. The encirclement of Soviet forces in Kiev was achieved on September 16. The encircled Soviets did not give up easily, a savage battle now ensued lasting for 10 days after which the Germans claimed over 600,000 Russian soldiers captured. Hitler called it the greatest battle in history. After Kiev, the Red Army no longer outnumbered the Germans and there were no more reserves. To defend Moscow, Stalin had only 800,000 men left. Operation Typhoon, the drive on Moscow began on October 2. In front of Army Group Center was a series of elaborate defense lines. The Germans easily penetrated the first defense line as 2nd Panzer Army returning from the south took Orel which was 75 miles behind the Russian first defense line. The Germans then pushed in and the vast pocket yielded 663,000 Russian prisoners. The Russians now had only 90,000 men and 1,500 tanks left for the defense for Moscow.

Almost from the beginning of Operation Typhoon the weather had deteriorated steadily, slowing the German advance on Moscow to as little as 2 miles a day. On October 31, the Germany Army High Command ordered a halt on Operation Typhoon as the armies were re-organized. The pause gave the Soviets time to build up new armies and bring in the Soviet troops from the east as the neutrality pact signed by the Soviets and Japanese in April, 1941 assured Stalin that there was no longer a threat from the Japanese.

On November 15, the Germans once again began the attack on Moscow. Facing the Germans were 6 Soviet Armies. The Germans intended to let the 3rd and 4th Panzer Armies cross the Moscow Canal and envelop Moscow from the North East. The 2nd Panzer Army would attack Tula and then close in on Moscow from the South and the 4th Army would smash in the center. However, on November 22, Soviet Siberian Troops were unleashed on the 2nd Panzer Army in the South which inflicted a shocking defeat on the Germans. The 4th Panzer Army succeeded in crossing the Moscow canal and on December 2 had penetrated to 15 miles of the Kremlin. But by then the first blizzards of the winter began and the Wehrmacht was not equipped for winter warfare. Frostbite and disease had caused more casualties than combat; dead and wounded had already reached 155,000 in 3 weeks and strength of divisions were now at 50% and the bitter cold had caused severe problems for guns and equipment. Weather conditions grounded the Luftwaffe. Newly built up Soviet troops near Moscow now numbered over 500,000 men and Zhukov on December 5 launched a massive counter attack which pushed the Germans back over 200 miles but no decisive breakthrough was achieved. The invasion of the Soviet Union had so far cost the Germans over 250,000 dead, 500,000 wounded and most of their tanks.
Soviet Siberian soldiers fighting during the Battle of Moscow.
Soviet Siberian soldiers fighting during the Battle of Moscow.

On January 6, 1942, Stalin, confident of his earlier victory, ordered a general counter-offensive. Initially the attacks made good ground as Soviet pincers closed around Demyansk and Vyazma and threatening attacks were made towards Smolensk and Bryansk. But despite these successes the Soviet offensive soon ran out of steam. By March, the Germans had recovered and stabilized their line and secured the neck of the Vyazma Pocket. Only at Demyansk was there any serious prospect of a major Soviet victory. Here a large part of the German 16th Army had been surrounded. Hitler ordered no withdrawal and the 92,000 men trapped in the pocket were to hold their ground while they were re-supplied by air. For 10 weeks they held out until April when a land corridor was opened to the west. The German forces retained Demyansk until they were permitted to withdraw in February 1943.

With the spring both sides decided to resume the offensive. While the German high command decided to stabilize the front at Kharkov, the Soviets unknowingly decided to attack in the same sector to maintain pressure in the south. The Soviets had attacked in Kharkov sector in January and had established a salient on the West Bank of the River Donets. On May 12, the Soviets opened with concentric attacks on either side of Kharkov and in both sides the Soviets broke through German lines and a serious threat to the city emerged. In response, the Germans accelerated the plans for their own offensive and launching it 5 days later.

The German 6th Army struck at the salient from the south and encircled the entire Soviet army assaulting Kharkov. In the last days of May, the Germans destroyed the forces inside the pocket. Of the Soviet troops inside the pocket, 70,000 were killed, 200,000 captured and only 22,000 managed to escape. The Germans did not realize the scale of the victory they had achieved, and unknown to the Germans, by early June the wide steppes of the Caucuses lay virtually undefended.

On June 28, 1942, the Axis began their summer offensive, Operation Blue, a planned drive southeast from the Don river to the Volga river toward the Caucasus mountains. German Army Group B planned to capture the city of Stalingrad, which would secure the German left flank, while Army Group A planned to capture the southern oil fields. In the Battle of the Caucasus, fought in the late summer and fall of 1942, the Axis forces captured the oil fields.
Soviet soldiers fighting in the ruins of Stalingrad, 1942
Soviet soldiers fighting in the ruins of Stalingrad, 1942

On August 23, 1942, the Germans reached the Volga north of Stalingrad. German bombing virtually destroyed the wooden buildings of the city which flanked the central strip, containing large modern factories. By September 23 1942, the main factory complex was surrounded and the German artillery was within range of the quays on the river, across which the Soviets evacuated wounded and brought in reinforcements. Ferocious street fighting, hand-to-hand conflict of the most savage kind, now ensued at Stalingrad. Exhaustion and deprivation gradually sapped men's strength. Hitler, who had become obsessed with the battle of Stalingrad, refused to countenance a withdrawal. General Paulus, in desperation, launched yet another attack early in November by which time the Germans had managed to capture 90% of the city. The Soviets, however, had been building up massive forces on the flanks of Stalingrad which were by this time severely undermanned as the bulk of the German forces had been concentrated in capturing the city. They launched Operation Uranus on November 19 1942, with twin attacks that met at the city of Kalach four days later and trapped the Sixth Army in Stalingrad.

The Germans requested permission to attempt a breakout, which was refused by Hitler, who ordered the Sixth Army to remain in Stalingrad where he promised they would be supplied by air until rescued. About the same time, the Soviets launched Operation Mars in a salient near the vicinity of Moscow. Its objective was to tie down Army Group Center and to prevent it from reinforcing Army Group South at Stalingrad.

In December, von Manstein hastily put together a German relief force of units composed from Army Group South to relieve the trapped Sixth Army. Unable to get reinforcements from Army Group Center, the relief force only managed to get within 50 kilometers (30 mi) before they were turned back by the Soviets. By the end of the year, the Sixth Army was in desperate condition, as the Luftwaffe was able to supply only about a sixth of the supplies needed.

Shortly before surrendering to the Red Army on February 2, 1943, Friedrich Paulus was promoted to Field Marshal. This was a message from Hitler, because no German Field Marshal had ever surrendered his troops or been taken alive. Only 91,000 German prisoners were taken, including 22 generals, of which only 5,000 men ever returned to Germany after the war. This was to be the greatest, and most costly, battle in terms of human life in history: about 2 million men were killed or wounded on both sides, including civilians, with Axis casualties estimated to be approximately 850,000.

The Pacific (April 1941 – June 1943)

Main articles: Pacific Ocean theater of World War II and South West Pacific theatre of World War II

The American battleships West Virginia and Tennessee under attack at Pearl Harbor
The American battleships West Virginia and Tennessee under attack at Pearl Harbor
Admiral Isoroku Yamamoto, Commander-in-Chief of the Imperial Japanese Navy, 1939–43
Admiral Isoroku Yamamoto, Commander-in-Chief of the Imperial Japanese Navy, 1939–43

Hitler kept his plan to invade the USSR secret from the Japanese. The USSR, fearing a two-front war, decided to make peace with Japan. On April 13, 1941, the USSR and Japan signed the Soviet-Japanese Neutrality Pact, thus allowing the Japanese to concentrate their attention to the upcoming war in Asia-Pacific.

In the summer of 1941, the United States, the United Kingdom, and the Netherlands began an oil embargo against Japan, threatening its ability to fight a major war at sea or in the air. However, Japanese forces continued to advance into China. Japan planned an attack on Pearl Harbor to cripple the U.S. Pacific Fleet, then seize oil fields in the Dutch East Indies.

On December 7, Japan launched virtually simultaneous surprise attacks against Pearl Harbor, Thailand and on the British territories of Malaya and Hong Kong. These attacks were on December 7, 1941 in western international time zones and on December 8 in the east. A Japanese carrier fleet launched an unexpected air attack on Pearl Harbor. The raid destroyed most of the American aircraft on the island and knocked the main American battle fleet out of action (three battleships were sunk, and five more were heavily damaged, though only USS Arizona and USS Oklahoma were permanently lost, the other six battleships were repaired and eventually returned to service). However, the four American aircraft carriers that had been the intended main target of the Japanese attack were off at sea. At Pearl Harbor, the main dock, supply, and repair facilities were quickly repaired. Furthermore, the base's fuel storage facilities, whose destruction could have crippled the Pacific fleet, were untouched. The attack united American public opinion to demand vengeance against Japan. The following day, December 8, the United States declared war on Japan.

Simultaneously with the attack on Hawaii, the Japanese attacked Wake Island, an American territory in the central Pacific. The initial landing attempt was repulsed by the garrison of marines, and fierce resistance continued until December 23. The Japanese sent heavy reinforcements, and the garrison surrendered when it became clear that no American relief force was coming.

Japan also invaded the Philippines, a U.S. Commonwealth, on December 8. American and Filipino forces, under General Douglas MacArthur, were forced to retreat to the Bataan Peninsula. Dogged resistance continued until April, buying precious time for the Allies. Following their surrender, the survivors were led on the Bataan Death March. Allied resistance continued for an additional month on the island fortress of Corregidor, until it too surrendered. General MacArthur, who had been ordered to retreat to Australia, vowed, "I shall return."

Disaster struck the British on December 10, as they lost two major battleships, HMS Prince of Wales and HMS Repulse. Both ships had been attacked by 85 Japanese bombers and torpedo planes based in Saigon, and 840 UK sailors perished. Churchill was to say of the event, "In all of the war I have never received a more direct shock."

Germany declared war on the United States on December 11, even though it was not obliged to do so under the Tripartite Pact. Hitler hoped that Japan would support Germany by attacking the Soviet Union. Japan did not oblige because it had signed a non-aggression treaty with the Soviet Union. Instead, Germany's declaration largely removed any significant opposition to the United States' joining the fight in the European Theater with full commitment.
U.S. Marines rest in the field on Guadalcanal, August-December 1942
U.S. Marines rest in the field on Guadalcanal, August-December 1942

The Allies were officially formed in the Declaration by United Nations on January 1, 1942. Soon afterwards, the American-British-Dutch-Australian Command (ABDACOM) was formed to unite Allied forces in South East Asia. It was the first Allied supreme command of the war.

On February 19, 1942, Roosevelt signed Executive Order 9066, leading to the internment of thousands of Japanese, Italians, German Americans, and some emigrants from Hawaii who fled after the bombing of Pearl Harbor for the duration of the war.

ABDACOM naval forces were all but destroyed in the Battle of the Java Sea—the largest naval battle of the war up that point—on February 28 through March 1. The joint command was wound up shortly afterwards, to be replaced by three Allied supreme commands in southern Asia and the Pacific.

In April, the Doolittle Raid, the first Allied air raid on Tokyo, boosted morale in the United States and caused Japan to shift resources to homeland defense, but did little physical damage.

In early May, the Japanese implemented Mo Sakusen (Operation Mo), a plan to take Port Moresby, New Guinea. The first stage was thwarted by the U.S. and Australian navies in the Battle of the Coral Sea. This was both the first battle fought between aircraft carriers, and the first battle where the opposing fleets never made direct visual contact. The American aircraft carrier Lexington was sunk and the Yorktown was severely damaged, while the Japanese lost the light carrier Shōhō and the large carrier Shōkaku suffered moderate damage. Zuikaku lost half of her air complement, and along with Shōkaku, was unable to participate in the upcoming battle at Midway. The battle was a tactical victory for the Japanese, as they inflicted heavier losses on the American fleet, but it was a strategic American victory, as the Japanese attack on Port Moresby was deflected.

In the six months after Pearl Harbor the Japanese had achieved nearly all of their naval objectives. Their fleet of eleven battleships, ten carriers, eighteen heavy and twenty light cruisers remained relatively intact. They had seriously damaged or sunk all U.S. battleships in the Pacific. The British and Dutch Far Eastern fleets had been destroyed, and the Royal Australian Navy had been driven back to port.[3] Their ring of conquests settled on a defensive perimeter of their choosing, extending from the Central Pacific to New Guinea to Burma.

Opposing this, the only significant strategic force remaining to the the Allies was the naval base at Pearl Harbor, including the U.S. Pacific Fleet's three aircraft carriers. Both sides viewed a decisive battle between aircraft carriers as inevitable, and the Japanese were confident in that they held a numerical advantage in heavy carriers of 10:3.[4] They also had an excellent carrier-based aircraft in the Zero. The Japanese sent a task force towards Midway Island, an outlier of the Hawaiian Islands, with the goal of drawing the remainder of the American fleet to battle. On June 5, American carrier-based dive-bombers sighted the Japanese force and sank four of Japan's best aircraft carriers in the Battle of Midway, at the cost of the carrier Yorktown. This was a major victory for the United States, and marked the turning point of the war in the Pacific. American shipbuilding and aircraft production vastly outpaced the Japanese, and the Japanese fleet would never again enjoy such numerical superiority.

In July, the Japanese attempted to take Port Moresby by land, along the Kokoda Track, a rugged, single-file path through the jungle and mountains. An outnumbered, untrained and ill-equipped Australian battalion—awaiting the return of regular units from North Africa and the U.S. Army—waged a fighting retreat against a 5,000-strong Japanese force.

On August 7, U.S. Marines began the Battle of Guadalcanal. For the next six months, U.S. forces fought Japanese forces for control of the island. Meanwhile, several naval encounters raged in the nearby waters, including the Battle of Savo Island, Battle of Cape Esperance, Naval Battle of Guadalcanal, and Battle of Tassafaronga.

In late August and early September, while battle raged on the Kokoda Track and Guadalcanal, an attack by Japanese marines at the eastern tip of New Guinea was defeated by Australian forces, in the Battle of Milne Bay. This was the first defeat for Japanese land forces during the Pacific War.

On January 22, after a bitter battle at Gona and Buna, Australian and U.S. forces took back the major Japanese beachheads in eastern New Guinea.

American authorities declared Guadalcanal secure on February 9. U.S., New Zealand, Australian and Pacific Island forces undertook the prolonged campaign to retake the occupied parts of the Solomon Islands, New Guinea, and the Dutch East Indies, experiencing some of the toughest resistance of the war. The rest of the Solomon Islands were retaken in 1943.

China and Southeast Asia (September 1941 – March 1944)

Main articles: Battle of Singapore and Battle of Changde

Lieutenant-General Arthur Percival, led by a Japanese officer, marches under a flag of truce to negotiate the capitulation of Allied forces in Singapore, on February 15, 1942. It was the worst defeat in British history.
Lieutenant-General Arthur Percival, led by a Japanese officer, marches under a flag of truce to negotiate the capitulation of Allied forces in Singapore, on February 15, 1942. It was the worst defeat in British history.

By 1940, the war had reached a stalemate with both sides making minimal gains. The United States provided heavy financial support for China and set up the Flying Tigers air unit to bolster Chinese air forces.

Japanese forces invaded northern parts of French Indo-China on September 22. The move was not unexpected, and followed a demand for bases in the region made two months earlier. Japanese relations with the west had deteriorated steadily in recent years and United States, having renounced the U.S.-Japanese trade treaty of 1911, placed embargoes on exports to Japan of war and other materials.

Less than 24 hours after the Attack on Pearl Harbor, Japan invaded Hong Kong. The Philippines and the British colonies of Malaya, Borneo, and Burma soon followed, with Japan's intention of seizing the oilfields of the Dutch East Indies. Despite fierce resistance by Philippine, Australian, New Zealand, British, Canadian, Indian, and American forces, all these territories capitulated to the Japanese in a matter of months. Singapore fell to the Japanese on February 15. Approximately 80,000 British Commonwealth personnel (along with 50,000 taken in Malaya), went into Japanese POW camps, representing the largest-ever surrender of British-led personnel. Churchill considered the British defeat at Singapore as one of the most humiliating British defeats of all time.
The Battle of Changde, called the Stalingrad of the East. China and Japan lost a combined total of 100,000 men in this battle.
The Battle of Changde, called the Stalingrad of the East. China and Japan lost a combined total of 100,000 men in this battle.

Japan launched a major offensive in China following the attack on Pearl Harbor. The aim of the offensive was to take the strategically important city of Changsha, which the Japanese had failed to capture on two previous occasions. For the attack, the Japanese massed 120,000 soldiers under four divisions. The Chinese responded with 300,000 men, and soon the Japanese army was encircled and had to retreat.

The Chinese Nationalist Kuomintang Army, under Chiang Kai-shek, and the Communist Chinese Army, under Mao Zedong, both opposed the Japanese occupation of China, but never truly allied against the Japanese. Conflict between Nationalist and Communist forces emerged long before the war; it continued after and, to an extent, even during the war, though less openly.

The Japanese had captured most of Burma, severing the Burma Road by which the Western Allies had been supplying the Chinese Nationalists. This loss forced the Allies to create a large sustained airlift from India, known as "flying the Hump". Under the American General Joseph Stilwell, Chinese forces in India were retrained and re-equipped, while preparations were made to drive the Ledo Road from India to replace the Burma Road. This effort was to prove an enormous engineering task.

The Atlantic (September 1939 - May 1945)

Main article: Battle of the Atlantic (1939-1945)

The U-Boat U-47 returns from sinking HMS Royal Oak, with the battlecruiser Scharnhorst in the background
The U-Boat U-47 returns from sinking HMS Royal Oak, with the battlecruiser Scharnhorst in the background
“ The only thing that ever really frightened me during the War was the U-boat peril. ”

— Winston Churchill

In the North Atlantic, German U-boats interdicted Allied transatlantic merchant shipping, attempting to cut supply lines to the United Kingdom and the USSR. One U-boat sank the British carrier HMS Courageous, while another managed to sink the battleship HMS Royal Oak in her home anchorage of Scapa Flow. Altogether, the U-boats sank more than 110 vessels in the first four months of the war.

In addition to U-boats, surface raiders posed a threat to Allied shipping. In the South Atlantic, the German pocket battleship Admiral Graf Spee sank nine British Merchant Navy vessels. She was tracked down off the coast of South America, then engaged by the cruisers HMS Ajax, HMS Exeter, and HMNZS Achilles in the Battle of the River Plate, and forced into Montevideo Harbor. Rather than face battle again, Captain Langsdorff made for sea and scuttled his battleship just outside the harbor.

On May 24, 1941, the German battleship Bismarck left port, threatening to break out into the Atlantic. She sank HMS Hood, one of the finest battlecruisers in the Royal Navy. A massive hunt ensued, in which the German battleship was sunk after a 1,700-mile (2,700 kilometer) chase. During this chase the British employed eight battleships and battle cruisers, two aircraft carriers, 11 cruisers, 21 destroyers, and six submarines. Fairey Swordfish torpedo bombers from aircraft carrier HMS Ark Royal struck the Bismarck, causing her rudder to jam and allowing the pursuing Royal Navy squadrons to catch and sink her.

Following the entry of the United States into the war in December 1941, U-boats sank shipping along the East Coast of the United States, the Caribbean Sea, and the Gulf of Mexico. They were initially so successful that this became known among U-boat crews as the Second happy time. Eventually, the institution of shore blackouts and an interlocking convoy system resulted in a drop in attacks and U-boats shifted their operations back to the mid-Atlantic.

On May 9, 1942 the destroyer HMS Bulldog captured a German U-Boat and recovered a complete, intact Enigma Machine, an encryption device. The machine was taken to Bletchley Park, England, where it was used to break the German code. Thereafter the Allies enjoyed an advantage in that they could intercept and understand some German radio communications, directing naval forces to where they would be most effective.
A German U-boat under attack by Allied aircraft
A German U-boat under attack by Allied aircraft

In December 1943, the last major sea battle between the Royal Navy and the German Navy took place. At the Battle of North Cape, Germany's last battlecruiser, the Scharnhorst, was sunk by HMS Duke of York, HMS Belfast, and several destroyers.

The turning point of the Battle of the Atlantic took place in early 1943 as the Allies refined their naval tactics, effectively making use of new technology to counter the U-Boats. The Allies produced ships faster than they were sunk, and lost fewer ships by adopting the convoy system. Improved anti-submarine warfare meant that the life expectancy of a typical U-boat crew would be measured in months. The vastly improved Type 21 U-boat appeared as the war was ending, but too late to affect the outcome.

The Western Front (September 1940 – June 1944)

Main article: Strategic bombing during World War II

Picture taken after the failed Canadian assault on the beach at Dieppe
Picture taken after the failed Canadian assault on the beach at Dieppe

Apart from Italy, Western Europe saw very little fighting from September 1940-June 1944. British and Canadian forces launched a small raid on the occupied French seaport of Dieppe, on August 19, 1942, whose aim was to test and gain information for an invasion of Europe which would happen later in the war. The Dieppe Raid was a total disaster but it provided critical information about amphibious tactics which would be utilized later in Operation Torch and Operation Overlord.

In December 1941, following the Japanese attack on Pearl Harbor which brought the United States into the war, Churchill and Roosevelt met at the Arcadia Conference. They agreed that defeating Germany had priority over defeating Japan. To relieve German pressure on the Soviet Union, the United States proposed a 1942 cross-channel invasion of France. The British opposed this, suggesting instead a small invasion of Norway or landings in French North Africa. The Declaration by the United Nations was issued, and the Western Allies invaded North Africa first.
The remains of German town of Wesel after intensive allied area bombing in 1945 (destruction rate 97% of all buildings)
The remains of German town of Wesel after intensive allied area bombing in 1945 (destruction rate 97% of all buildings)

With the entry of the United States into the War, the aerial war turned in favor of the Allies by late 1942. The U.S. air force began the first daylight bombing of Germany, which allowed for more precise targeting but exposed the attackers to more danger. Meanwhile the British and the Canadians bombed Germany during the night targeting German cities and war industries. This effort was orchestrated by Air Chief Marshall Harris, who became known as 'Bomber Harris'. Additionally, Winston Churchill ordered "terror raids" intended to wipe out whole cities in one go, by incendiary devices causing firestorms, thus depriving German workers of their homes. Mass raids involving upwards of 500 to 1000 heavy bombers at a time were undertaken against airfields, industrial centers, submarine bases, rail-marshalling yards, oil depots and, in the later stages of the war, launching sites for weapons such as the V-1 missile (nicknamed 'doodlebug'), the V-2 rocket and a jet-engined plane, the Messerschmitt Me 262. The Luftwaffe was overwhelmed and had only a few operational planes left by late 1944 on the Western Front. By 1945, all major German cities were burnt-out ruins.

The Allies also began sabotage missions against Germany such as Operation Anthropoid in which Reinhard Heydrich, the architect of the Final Solution was assassinated in May 1942 by Czech resistance agents send flow in from the United Kingdom. Hitler ordered severe reprisals against the occupants of the nearby Czechoslovakian village of Lidice. All the while, the Allies continued to build up their forces in the United Kingdom for an eventual invasion of Western Europe which was planned for late spring or early summer of 1944.

The Mediterranean (May 1943 – March 1945)

Main article: Italian Campaign (World War II)

The surrender of Axis forces in Tunisia on May 13, 1943, yielded some 250,000 prisoners. The North African war proved to be a disaster for Italy, and when the Allies invaded Sicily on July 10 in Operation Husky, capturing the island in a little over a month, the regime of Benito Mussolini collapsed. On July 25, he was removed from office by Victor Emmanuel III, the King of Italy, and arrested with the positive consent of the Great Fascist Council. A new government, led by Pietro Badoglio, took power and declared ostensibly that Italy would stay in the war. Badoglio had already begun secret peace negotiations with the Allies.

The Allies invaded mainland Italy on September 3, 1943. Italy surrendered to the Allies on September 8, as had been agreed in negotiations. The royal family and Badoglio government escaped to the south, leaving the Italian army without orders, while the Germans took over the fight, forcing the Allies to a complete halt in the winter of 1943–44 at the Gustav Line south of Rome.

In the north, Mussolini, with Nazi support, created what was effectively a puppet state, the Italian Social Republic or Republic of Salò, named after the new capital of Salò on Lake Garda.

Mid-1943 brought the fifth and final German Sutjeska offensive against the Yugoslav partisans.
Cassino is destroyed after heavy bombardment
Cassino is destroyed after heavy bombardment

Following Italy's surrender, German troops took over the defense of the Italian peninsula and established the Gustav line in the southern Apennine Mountains south of Rome. The Allies were unable to break this line, and so attempted to bypass it with an amphibious landing at Anzio on January 22, 1944. The landing, named Operation Shingle, quickly became encircled by the Germans and bogged down, leading Churchill to comment, "Instead of hurling a wildcat onto the shore all we got was a stranded whale."

Unable to circumvent the Gustav line, the Allies again attempted to break through with frontal assaults. On February 15, the monastery of Monte Cassino, founded in 524 by St. Benedict was destroyed by American B-17 and B-26 bombers. Crack German paratroopers poured back into the ruins to defend it. From January 12 to May 18, it was assaulted four times by Allied troops, for a loss of over 54,000 Allied and 20,000 German soldiers.

After months, the Gustav line was broken and the Allies marched north. On June 4, Rome was liberated, and the Allied army reached Florence in August. It then was held at the Gothic Line on the Tuscan Apennines during the winter.

The Eastern Front (February 1943 – January 1945)

Main articles: Third Battle of Kharkov, Battle of Kursk, Battle of the Lower Dnieper, Operation Bagration, and Lvov-Sandomierz Offensive

Soviet soldiers crossing the River Dneiper under German fire.
Soviet soldiers crossing the River Dneiper under German fire.

After the surrender of the German Sixth Army at Stalingrad on February 2, 1943, the Red Army launched eight offensives during the winter. Many were concentrated along the Don basin near Stalingrad. These attacks resulted in initial gains until German forces were able to take advantage of the over extended and weakened condition of the Red Army and launch a counter attack to re-capture the city of Kharkov and surrounding areas. This was to be the last major strategic German victory of World War II.
Waffen-SS Panzergrenadiers and Tiger tanks of the SS Panzergrenadier Division Totenkopf during the start of Operation Zitadelle
Waffen-SS Panzergrenadiers and Tiger tanks of the SS Panzergrenadier Division Totenkopf during the start of Operation Zitadelle

The rains of spring inhibited campaigning in the Soviet Union, but both sides used the interval to build up for the inevitable battle that would come in the summer. The start date for the offensive had been moved repeatedly as delays in preparation had forced the Germans to postpone the attack. By July 4, the Wehrmacht, after assembling their greatest concentration of firepower during the whole of World War II, launched their offensive against the Soviet Union at the Kursk salient. Their intentions were known by the Soviets, who hastened to defend the salient with an enormous system of earthwork defenses. The Germans attacked from both the north and south of the salient and hoped to meet in the middle, cutting off the salient and trapping 60 Soviet divisions. The German offensive in the Northern sector was ground down as little progress was made through the Soviet defenses but in the Southern Sector there was a danger of a German breakthrough. The Soviets then brought up their reserves to contain the German thrust in the Southern sector, and the ensuing Battle of Kursk became the largest tank battle of the war, near the city of Prokhorovka. The Germans lacking any sizable reserves had exhausted their armored forces and could not stop the Soviet counteroffensive that threw them back across their starting positions.

The Soviets captured Kharkov following their victory at Kursk and with the Autumn rains threatening, Hitler agreed to a general withdrawal to the Dnieper line in August. As September proceeded into October, the Germans found the Dnieper line impossible to hold as the Soviet bridgeheads grew. Important Dnieper towns started to fall, with Zaporozhye the first to go, followed by Dnepropetrovsk. Early in November the Soviets broke out of their bridgeheads on either side of Kiev and recaptured the Ukrainian capital. The 1st Ukrainian Front attacked at Korosten on Christmas Eve, and the Soviet advance continued along the railway line until the 1939 Soviet-Polish border was reached.
Soviet advances from August 1943 to December 1944.
Soviet advances from August 1943 to December 1944.

The Soviets launched their winter offensive in January 1944 in the Northern sector and relieved the brutal siege of Leningrad. The Germans conducted an orderly retreat from the Leningrad area to a shorter line based on the lakes to the south. By March the Soviets struck into Romania from Ukraine. The Soviet forces encircled the First Panzer Army north of the Dniestr river. The Germans escaped the pocket in April, saving most of their men but losing their heavy equipment. During April, the Red Army launched a series of attacks near the city of Iaşi, Romania, aimed at capturing the strategically important sector which they hoped to use as a springboard into Romania for a summer offensive. The Soviets were held back by the German and Romanian forces when they launched the attack through the forest of Târgul Frumos as Axis forces successfully defended the sector through the month of April.

As Soviet troops neared Hungary, German troops occupied Hungary on March 20. Hitler thought that Hungarian leader Admiral Miklós Horthy might no longer be a reliable ally. Germany's other Axis ally, Finland had sought a separate peace with Stalin in February 1944, but would not accept the initial terms offered. On June 9, the Soviet Union began the Fourth strategic offensive on the Karelian Isthmus that, after three months, forced Finland to accept an armistice.

Before the Soviet could begin their Summer offensive into Belarus they had to clear the Crimea peninsula of Axis forces. Remnants of the German Seventeenth Army of Army Group South and some Romanian forces were cut off and left behind in the peninsula when the Germans retreated from the Ukraine. In early May, the Red Army's 3rd Ukrainian Front attacked the Germans and the ensuing battle was a complete victory of the Soviet forces and a botched evacuation effort across the Black Sea by Germany failed.

With the Crimea cleared, the long awaited Soviet summer offensive codenamed, Operation Bagration, began on June 22, 1944 which involved 2.5 million men and 6,000 tanks. Its objective was to clear German troops from Belarus and crush German Army Group Center which was defending that sector. The offensive was timed to coincide with the Allied landings in Normandy but delays caused the offensive to be postponed for a few weeks. The subsequent battle resulted in the destruction of German Army Group Centre and over 800,000 German casualties, the greatest defeat for the Wehrmacht during the war. The Soviets swept forward, reaching the outskirts of Warsaw on July 31.
Ruins of the Bank Polski after the Warsaw Uprising
Ruins of the Bank Polski after the Warsaw Uprising

The proximity of the Red Army led the Poles in Warsaw to believe they would soon be liberated. On August 1, they revolted as part of the wider Operation Tempest. Nearly 40,000 Polish resistance fighters seized control of the city. The Soviets, however, did not advance any further. [1] The only assistance given to the Poles was artillery fire, as German army units moved into the city to put down the revolt. The resistance ended on October 2. German units then destroyed most of what was left of the city.
Bucharesters greet Romania's new ally, the Red Army, on 31 August 1944.
Bucharesters greet Romania's new ally, the Red Army, on 31 August 1944.

Following the destruction of German Army Group Center, the Soviets attacked German forces in the south in mid-July 1944, and in a month's time they cleared Ukraine of German presence inflicting heavy losses on the Germans. Once Ukraine had been cleared the Soviet forces struck into Romania. The Red Army's 2nd and 3rd Ukrainian Fronts engaged German Heeresgruppe Südukraine, which consisted of German and Romanian formations, in an operation to occupy Romania and destroy the German formations in the sector. The result of the Battle of Romania was a complete victory for the Red Army, and a switch of Romania from the Axis to the Allied camp. Bulgaria surrendered to the Red Army in September. Following the German retreat from Romania, the Soviets entered Hungary in October 1944 but the German Sixth Army encircled and destroyed three corps of Marshal Rodion Yakovlevich Malinovsky's Group Pliyev near Debrecen, Hungary. The rapid assault the Soviets had hoped that would lead to the capture of Budapest was now halted and Hungary would remain Germany's ally until the end of the war in Europe. This battle would be the last German victory in the Eastern Front.

The Soviets recovered from their defeat in Debrecen and advancing columns of the Red Army liberated Belgrade in late December and reached Budapest on December 29, 1944 and en-circled the city where over 188,000 Axis troops were trapped including many German Waffen-SS. The Germans held out till February 13, 1945 and the siege became one of the bloodiest of the war. Meanwhile the Red Army's 1st, 2nd, and 3rd Baltic Fronts engaged the remnants of German Army Group Center and Army Group North to capture the Baltic region from the Germans in October 1944. The result of the series of battles was a permanent loss of contact between Army Groups North and Centre, and the creation of the Courland Pocket in Latvia where the entire German Eighteenth Army which fielded twenty Infantry and two Panzer divisions were trapped and would remain there till the end of the war.

The Pacific (June 1943 – July 1945)

Main articles: New Guinea campaign, Solomon Islands campaign, Gilbert and Marshall Islands campaign, Mariana and Palau Islands campaign, Philippines campaign (1944-45), Battle of Iwo Jima, and Battle of Okinawa

On June 30, the Allies launched Operation Cartwheel, a grand strategy for the South and South West Pacific, aimed at isolating the major Japanese base at Rabaul, before proceeding on an "island-hopping" campaign towards Japan. Three main objectives were identified: recapturing Tulagi and the Santa Cruz Islands; recapturing the north coast of New Guinea, and the central Solomon Islands and; the reduction of Rabaul and related bases.

By September, Australian and U.S. forces in New Guinea had captured the major Japanese bases at Salamaua and Lae. Soon afterwards they launched the Huon Peninsula, the Finisterre Range, Bougainville, and New Britain campaigns.

In November, U.S. Marines won the Battle of Tarawa. This was the first heavily opposed amphibious assault in the Pacific theater. The high casualties taken by the Marines sparked off a storm of protest in the United States, where the large losses could not be understood for such a tiny and seemingly unimportant island. The Allies adopted a policy of bypassing some Japanese island strongholds and letting them "wither on the vine", cut off from supplies and troop reinforcements.

The Allied advance continued in the Pacific with the capture of the Marshall Islands before the end of February. Some 42,000 U.S. Army soldiers and U.S. Marines landed on Kwajalein atoll on January 31. Fierce fighting occurred, and the island was taken on February 6. U.S. Marines next defeated the Japanese in the Battle of Eniwetok.

The U.S. strategic objective was to gain airbases within bombing range of the new B-29s on the Mariana Islands, especially Saipan, Tinian and Guam. On June 11, the U.S. Naval fleet bombarded Saipan, defended by 32,000 Japanese troops; 77,000 Marines landed starting the 15th, and the island was secure by July 9. The Japanese committed much of their declining naval strength in the Battle of the Philippine Sea, but suffered severe losses in both ships and aircraft. After the battle, the Japanese aircraft carrier force was no longer militarily effective. With the capture of Saipan, Japan was finally within range of B-29 bombers.

Guam was invaded on July 21 and taken on August 10, but the Japanese fought fanatically. Mopping-up operations continued long after the Battle of Guam was officially over. The island of Tinian was invaded on July 24 and was conquered on August 1. This operation saw the first use of napalm in the war.[citation needed]
"I have returned." — A famous photo of Gen. MacArthur coming ashore back to the Philippines. Photo taken by Carl Mydans of Life magazine.
"I have returned." — A famous photo of Gen. MacArthur coming ashore back to the Philippines. Photo taken by Carl Mydans of Life magazine.

General MacArthur's troops liberated the Philippines, landing on the island of Leyte on October 20. The Japanese had prepared a rigorous defense and used the last of their naval forces in a failed attempt to destroy the invasion force in the Battle of Leyte Gulf, October 23 through October 26, 1944, arguably the largest naval battle in history. This was the first battle that employed Japanese kamikaze attacks. The Japanese battleship Musashi, one of the two largest battleships ever built, was sunk by 19 American torpedoes and 17 bombs.

Throughout 1944, Allied submarines and aircraft attacked Japanese merchant shipping and deprived Japan's industry of the raw materials it had gone to war to obtain. The main target was oil, and Japan ran almost dry by late 1944. In 1944, submarines sank over two million tons of cargo,[5] while the Japanese were only able to replace less than one million tons.[6]

In January 1945, the U.S. Sixth Army landed on Luzon, the main island of the Philippines. Manila was recaptured by March.

The United States captured Iwo Jima in February. The island was psychologically important because it was traditional Japanese territory, administered by the Tokyo prefecture. It was heavily defended with many underground entrenchments, but was eventually taken by Marines after they captured Mount Suribachi, a keystone of the defense. Iwo Jima proved invaluable because of its two airfields that were used for emergency landings for B29's and because it was close enough to provide fighter escort that could reach the Japanese Home Islands.[7]

With the subsequent capture of Okinawa (April through June), the U.S. brought the Japanese homeland within easier range of naval and air attack. The Japanese defended the island with ground forces, kamikazes, and with the one-way suicide mission of the battleship Yamato, which was sunk by American dive-bombers. Amongst dozens of other Japanese cities, Tokyo was firebombed, and about 90,000 people died from the initial attack. The dense living conditions around production centres and the wooden residential constructions contributed to the large loss of life. In addition, the ports and major waterways of Japan were extensively mined by air in Operation Starvation, which seriously disrupted the logistics of the island nation.

The last major offensive in the South West Pacific Area was the Borneo campaign of mid-1945, which was aimed at further isolating the remaining Japanese forces in Southeast Asia and securing the release of Allied prisoners of war.

China and Southeast Asia (March 1944 – June 1945)

Main articles: Battle of Henan-Hunan-Guangxi and Battle of Imphal

The Indian Army's Gurkha Rifles crossing the Irrawaddy River on 27 January 1945. The Gurkhas were involved in hard fought actions with the Japanese during the early months of 1945.
The Indian Army's Gurkha Rifles crossing the Irrawaddy River on 27 January 1945. The Gurkhas were involved in hard fought actions with the Japanese during the early months of 1945.

In April 1944, the Japanese launched Operation Ichigo, to secure the railway route from Peking to Nanking, and to clear southern China of American airfields under the command of General Chennault.[8] The operation was successful in that it opened a continuous corridor from Peking to Indochina, and the airfields were forced to relocate inland. However it failed to destroy the army of Chiang Kai-shek, and the Americans soon acquired the Marianas, from which they could bomb the Japanese Home Islands.

While the Americans steadily built the Ledo Road from India to China, in March 1944, the Japanese began their own offensive into India. This "march to Delhi" was instigated by local commanders, and the leadership of the Japanese auxiliaries, the Indian National Army. The Japanese attempted to destroy the main British and Indian forces at Imphal, resulting in some of the most ferocious fighting of the war. While the encircled allied troops were reinforced and resupplied by transport aircraft until fresh troops broke the siege, the Japanese ran out of supplies and starved. They eventually retreated losing 85,000 men, one of the largest Japanese defeats of the war.

During the monsoon from August to November 1944, the Japanese were pursued to the Chindwin River in Burma. With the onset of the dry season in early 1945, while the American and Chinese forces finally completed the Ledo Road, although too late to have any decisive effect, the British Fourteenth Army, consisting of Indian, British, and African units, launched an offensive into Central Burma. The Japanese forces were heavily defeated, and the Allies pursued them southward, taking Rangoon on May 2 (see Operation Dracula).

The Western Front (June 1944 – January 1945)

Main articles: Battle of Normandy, Operation Market Garden, and Battle of the Bulge

American troops disembark in the surf at Omaha Beach on D-Day, 6 June 1944.
American troops disembark in the surf at Omaha Beach on D-Day, 6 June 1944.

On "D-Day" (June 6, 1944), the western Allies of mainly the United States, the United Kingdom, and Canada invaded German-held Normandy.[9] Prior to this the Germans had constructed an elaborate series of fortifications along the coast called the Atlantic Wall. The Allied forces under supreme command of Dwight D. Eisenhower had launched an elaborate deception campaign to convince the Germans that the landings would occur in the Calais area which caused the Germans to deploy the German Seventh Army and Fifth Panzer Army in that sector. Only three days after the invasion did the German high command realize that Normandy was the actual invasion but by then the Allies had already consolidated their beachheads. The British had hoped to capture Caen on the first day but that proved too ambitious. The British launched another attack a few days later but were held back as the Germans had moved in large number of troops to hold the city. The city was to remain in German hands for another 6 weeks. The bocage terrain of Normandy where the Americans had landed made it ideal ground for defensive warfare. Nevertheless, they made steady progress and captured the deep-water port of Cherbourg on June 26, one of the primary objectives of the invasion. However, the Germans had mined the harbor and destroyed most of the port facilities before surrendering, and it would be another month before the port could be brought back into limited use.
British Troops take cover on Sword Beach
British Troops take cover on Sword Beach

Allied firepower, improved tactics, and numerical superiority eventually resulted in a breakout of American mechanized forces at the western end of the Normandy pocket in Operation Cobra on July 23. When Hitler learned of the American breakout, he ordered his forces in Normandy to launch an immediate counter-offensive. However the German forces moving in open countryside were now easily targeted by Allied aircraft, as they had initially escaped Allied air attacks due to their well camouflaged defensive positions.

The Americans placed strong formations on their flanks which blunted the attack and then began to encircle the 7th Army and 5th Panzer Army in the Falaise Pocket. Some 50,000 Germans were captured, but 100,000 managed to escape the pocket. Worse still, the British and Canadians who had been bogged down in their sector now began to break through the German lines. Any hope the Germans had of containing the Allied thrust into France by forming new defensive lines was now gone. The German forces retreated into Northern France, Holland and Belgium. By August 1944, Allied forces stationed in Italy invaded the French Riviera on August 15 and linked up with forces from Normandy. The clandestine French Resistance in Paris rose against the Germans on August 19, and a French armored division under General Philippe Leclerc, pressing forward from Normandy, received the surrender of the German forces there and liberated the city on August 25.
American troops march down the Champs Elysées in Paris
American troops march down the Champs Elysées in Paris
A V-1 flying bomb in flight
A V-1 flying bomb in flight

The Germans launched the V-1 flying bomb, the world's first cruise missile to attack targets in UK. Later, they would employ the V-2 rocket, a liquid-fuelled guided ballistic missile. However the weapon was not accurate and could only target large targets like cities and thus was not able to play a decisive role in the war.
British paratroopers land during Operation Market Garden
British paratroopers land during Operation Market Garden

Logistical problems plagued the Allies' advance east as the supply lines still ran back to the beaches of Normandy. Allied paratroopers and armor attempted a war-winning advance through the Netherlands and across the Rhine River with Operation Market Garden in September, but they were repulsed. A decisive victory by the Canadian First Army in the Battle of the Scheldt secured the entrance to the port of Antwerp, which freed it to receive supplies by late November 1944. Meanwhile, the Americans launched an attack through the Hurtgen Forest in September; the Germans, despite having smaller numbers, were able to use the difficult terrain and good defensive positions to hold back the Americans for over 5 months. In October, the Americans captured Aachen, the first major German city to be occupied.

In December 1944, the German Army made its last major offensive in the West, known as the Battle of the Bulge. With Hitler's Eastern flank collapsing in, he sought victory similar to the 1940 Ardennes offensive, which he envisioned would drive back the Western Allies and force them to agree to a separate peace. Poor weather during the initial days of the offensive favored the Germans, because Allied aircraft were grounded. At first, the Germans scored successes against the unprepared Allied forces. The lead group of panzers, Kampfgruppe Peiper led by Jochen Peiper, got so far out in front that he created a "bulge" in the American lines, hence the name of the battle.

Stubborn U.S. resistance at St. Vith and by the surrounded 101st Airborne Division at Bastogne, an important crossroads, blunted the German advance. The arrival of the U.S. Third Army under General George Smith Patton, Jr. ended the German threat, and further counterattacks trapped many German units in the resulting pocket. On January 7, Hitler gave the order for his remaining forces to retreat. It was the bloodiest battle in U.S. military history.

The Eastern Front (January 1945 – April 1945)

Main articles: Vistula-Oder Offensive and Battle of Berlin

Berlin and Prague offensive on the Eastern Front, 1945.
Berlin and Prague offensive on the Eastern Front, 1945.
Marshal of the Soviet Union Georgiy Konstantinovich Zhukov.
Marshal of the Soviet Union Georgiy Konstantinovich Zhukov.

On January 12, the Soviet Army was ready for its next big offensive. Konev’s armies attacked the Germans in southern Poland and expanded out from their Vistula River bridgehead near Sandomierz. On January 14, Rokossovskiy’s armies attacked from the Narew River north of Warsaw. Zhukov's armies in the centre attacked from their bridgeheads near Warsaw. The combined Soviet offensive broke the defences covering East Prussia, leaving the German front in chaos.

Zhukov took Warsaw by January 17 and by January 19, his tanks took Łódź. That same day, Konev's forces reached the German pre-war border. At the end of the first week of the offensive, the Soviets had penetrated 160 kilometers (100 mi) deep on a front that was 650 kilometers (400 mi) wide. The Soviet onslaught finally halted on the Oder River at the end of January, only 60 kilometers (40 mi) from Berlin.

The Soviets had hoped to capture Berlin by mid-February but that proved hopelessly optimistic. German resistance which had all but collapsed during the initial phase of the attack had stiffened immeasurably. The Russian supply lines were over extended and discipline among Soviet troops as they were unleashed on German territory all but collapsed. The spring thaw, the lack of air support, and fear of encirclement through flank attacks from East Prussia, Pommern and Silesia led to a general halt in the Soviet offensive. The newly created Army Group Vistula, under the command of Heinrich Himmler, attempted a counter-attack on the exposed flank of the Soviet Army but failed by February 24. This made it clear to Zhukov that the flank had to be secure before any attack on Berlin could be mounted. The Soviets then re-organized their forces and then struck north and cleared Pomerania and Silesia of German troops. In the south, three German attempts to relieve the encircled Budapest garrison failed, and the city fell to the Soviets on February 13. Again the Germans counter-attacked; Hitler insisting on the impossible task of regaining the Danube River. By March 16, the attack had failed, and the Red Army counter-attacked the same day. On March 30, they entered Austria and captured Vienna on April 13.
Red Army soldiers raising the Soviet flag on the roof of the Reichstag in Berlin, Germany
Red Army soldiers raising the Soviet flag on the roof of the Reichstag in Berlin, Germany

Hitler had believed that the main Soviet target for their upcoming offensive would be in the south near Prague and not Berlin and had send the last remaining German reserves to defend that sector. The Red Army's main goal was in fact Berlin and by April 16 it was ready to begin its final assault on Berlin. Zhukov's forces struck from the center and crossed the Oder river but got bogged down under stiff German resistance around Seelow Heights. After three days of very heavy fighting and 30,000 Russian soldiers dead, the last defenses of Berlin was breached. Konev crossed the Oder river from the South and was within striking distance of Berlin but Stalin ordered Konev to guard the flanks of Zhukov's forces and not attack Berlin, as Stalin had promised the capture of Berlin to Zhukov[citation needed]. Rokossovskiy’s forces crossed the Oder from the North and linked up with British Field Marshal Bernard Montgomery's forces in northern Germany while the forces of Zhukov and Konev captured Berlin.

By April 24, the Soviet army groups had encircled the German Ninth Army and part of the 4th Panzer Army. These were main forces that were supposed to defend Berlin but Hitler had issued orders for these forces to hold their ground and not retreat. Thus the main German forces which were suppose to defend Berlin were trapped south east of the Berlin. The city was encircled around the same time and as a final resistance effort, Hitler called for civilians, including teenagers and the elderly, to fight in the Volkssturm militia against the oncoming Red Army. Those marginal forces were augmented by the battered German remnants who had fought the Soviets in Seelow Heights. Hitler ordered the encircled Ninth Army to break out and link up with the Twelfth Army of General Walther Wenck and relieve Berlin. An impossible task, the surviving units of the Ninth Army were instead driven into the forests around Berlin near the village of Halbe where they were involved in particularly fierce fighting trying to break through the Soviet lines and reach the Twelfth Army. A minority managed to join with the Twelfth Army and fight their way west to surrender to the Americans. Meanwhile the fierce urban fighting continued in Berlin. The Germans had stockpiled a very large quantity of panzerfausts and took a very heavy toll on Soviet tanks in the rubble filled streets of Berlin. However, the Soviets employed the lessons they learned during the urban fighting of Stalingrad and were slowly advancing to the center of the city. German forces in the city resisted tenaciously, in particular the SS Nordland which was made of foreign SS volunteers, because they were ideologically motivated and they believed that they would not live if captured. The fighting was house-to-house and hand-to-hand. The Soviets sustained 360,000 casualties; the Germans sustained 450,000 including civilians and above that 170,000 captured. Hitler and his staff moved into the Führerbunker, a concrete bunker beneath the Chancellery, where on April 30, 1945, he committed suicide, along with his bride, Eva Braun.

War ends in Europe

Main articles: Yalta Conference, End of World War II in Europe, and Prague Offensive

On January 14, the U.S. XII Corps and British 2nd Army launched Operation Blackcock in order to clear the Roer Triangle, a German-held salient between the rivers Maas and Roer south of Roermond. By January 27, the German forces were driven east of the Roer.
Winston Churchill, Franklin D. Roosevelt, and Joseph Stalin at Yalta in 1945.
Winston Churchill, Franklin D. Roosevelt, and Joseph Stalin at Yalta in 1945.

Meanwhile, Roosevelt, Churchill, and Stalin made arrangements for post-war Europe at the Yalta Conference in February 1945. Their meeting resulted in many important resolutions such as the formation of the United Nations, democratic elections in Poland, borders of Poland moved westwards at the expense of Germany, Soviet nationals were to be repatriated and it was agreed that Soviet Union would attack Japan within three months of Germany's surrender.
U.S. General Omar Bradley led the advance into Germany
U.S. General Omar Bradley led the advance into Germany

The Allies resumed their advance into Germany in late January. The final obstacle to the Allies was the river Rhine, which was crossed in late March 1945, aided by the fortuitous capture of the Ludendorff Bridge at Remagen. Once the Allies had crossed the Rhine, the British fanned out northeast towards Hamburg, crossing the river Elbe and moving on towards Denmark and the Baltic Sea. The U.S. 9th Army went south as the northern pincer of the Ruhr encirclement, and the U.S. 1st Army went north as the southern pincer of the Ruhr encirclement. These armies were commanded by General Omar Bradley who had over 1,300,000 men under his control. On April 4, the encirclement was completed, and the German Army Group B commanded by Field Marshal Walther Model was trapped in the Ruhr Pocket. Some 300,000 German soldiers became prisoners of war. The 1st and 9th U.S. armies then turned east. They halted their advance at the Elbe river where they met up with Soviet troops in mid-April.

Allied advances in the winter of 1944–45 up the Italian peninsula had been slow because of the mountains and troop re-deployments to France. By April 9, the British/American 15th Army Group broke through the Gothic Line and attacked the Po Valley, gradually enclosing the main German forces. Milan was taken by the end of April. The U.S. 5th Army continued to move west and linked up with French units. The New Zealand Second Division entered Trieste to confront Yugoslav partisans, who were intending to make the city part of Yugoslavia.

A few days before the surrender of German troops in Italy, Italian partisans captured Mussolini trying to make his escape to Switzerland. He was executed, along with his mistress, Clara Petacci. Their bodies were taken to Milan and hung upside down on public display.
Marshals of the Soviet Union Zhukov (on the white horse) and Rokossovskiy at the Victory Parade in Red Square on June 24, 1945.
Marshals of the Soviet Union Zhukov (on the white horse) and Rokossovskiy at the Victory Parade in Red Square on June 24, 1945.

Grand Admiral Karl Dönitz became leader of the German government after the death of Hitler, but the German war effort quickly disintegrated. German forces in Berlin surrendered the city to Soviet troops on May 2, 1945.

The German forces in Italy surrendered on May 2, 1945, at General Alexander's headquarters, and German forces in northern Germany, Denmark, and the Netherlands surrendered on May 4. The surrender in Italy was preceded by the controversial secret Operation Sunrise in March 1945, during which the Great Britain and the United States were accused by the Soviet Union of trying to reach a separate peace. The German High Command under Generaloberst Alfred Jodl surrendered unconditionally all remaining German forces on May 7 in Rheims, France. The western Allies celebrated "V-E Day" on May 8.

The Soviet Union celebrated "Victory Day" on May 9. Some remnants of German Army Group Center continued resistance until May 11 or May 12 (see Prague Offensive). [2]

War ends in Asia

Main articles: Potsdam Conference, Atomic bombings of Hiroshima and Nagasaki, and Operation August Storm

Chiang Kai-shek and Mao Zedong met in the wartime capital of Chongqing, to toast to the Chinese victory over Japan.
Chiang Kai-shek and Mao Zedong met in the wartime capital of Chongqing, to toast to the Chinese victory over Japan.

The last Allied conference of World War II was held at the suburb of Potsdam, outside Berlin, from July 17 to August 2. During the Potsdam Conference, agreements were reached among the Allies on policies for occupied Germany. An ultimatum was issued calling for the unconditional surrender of Japan.
The mushroom cloud resulting from the nuclear weapon known as Fat Man rises 18 km (11 mi, 60,000 ft) over Nagasaki from the nuclear explosion hypocenter.
The mushroom cloud resulting from the nuclear weapon known as Fat Man rises 18 km (11 mi, 60,000 ft) over Nagasaki from the nuclear explosion hypocenter.

U.S. president Harry Truman decided to use the new atomic weapon to bring the war to a swifter end. The battle for Okinawa had shown that an invasion of the Japanese mainland (planned for November) would result large numbers of American casualties. The official estimate given to the Secretary of War was 1.4 to four million Allied casualties, though some historians dispute whether this would have been the case. Invasion would have meant the death of millions of Japanese soldiers and civilians, who were being trained as militia.

On August 6, 1945, a B-29 Superfortress, the Enola Gay, dropped a nuclear weapon dubbed Little Boy on Hiroshima, destroying the city. On August 9, a B-29 named Bockscar dropped the second atomic bomb, dubbed Fat Man, on the port city of Nagasaki.

On August 8, two days after the atomic bomb was dropped on Hiroshima, the Soviet Union, having renounced its nonaggression pact with Japan in April, attacked the Japanese in Manchuria, fulfilling its Yalta pledge to attack the Japanese within three months after the end of the war in Europe. The attack was made by three Soviet army groups. In less than two weeks, the Japanese army in Manchuria, consisting of over a million men, had been destroyed by the Soviets. The Red Army moved into North Korea on August 18. Korea was subsequently divided at the 38th parallel into Soviet and U.S. zones.

The American use of atomic weapons against Japan and the Soviet invasion of Manchukuo prompted Hirohito to bypass the existing government and intervene to end the war. In his radio address to the nation, the Emperor did not mention the entry of the Soviet Union into the war, but in his "Rescript to the soldiers and sailors" of August 17, ordering them to cease fire and lay down arms, he stressed the relationship between Soviet entrance into the war and his decision to surrender, omitting any mention of the atomic bombs.

The Japanese surrendered on August 14, 1945, or V-J day, signing the Japanese Instrument of Surrender on September 2. The Japanese troops in China formally surrendered to the Chinese on September 9, 1945. See image

Casualties, civilian impact, and atrocities

Main articles: World War II casualties, The Holocaust, Concentration camp, Gulag, Japanese American internment, and War crimes during World War II

Major deportation routes to Nazi extermination camps during The Holocaust, Aktion T-4 and alike.
Major deportation routes to Nazi extermination camps during The Holocaust, Aktion T-4 and alike.

Some 63 million people, or 3% of the world population, died in the war (though estimates vary): about 24 million soldiers and 38 million civilians. This total includes the estimated 9 million lives lost in the Holocaust. Of the total deaths in World War II, approximately 80% were on the Allied side and 20% on the Axis side.[10]

Allied forces suffered approximately 17 million military deaths, of which about 11 million were Soviet and 3 million Chinese. Axis forces suffered about 8 million, of which more than 5 million were German. In total, of the military deaths in World War II, approximately 44% were Soviet soldiers, 22% were German, 12% were Chinese, 8% were Japanese, 9% were soldiers of other Allied forces, and 5% were other Axis country soldiers. Some modern estimates double the number of Chinese casualties originally stated.[10] Of the civilian deaths, approximately 90% were Allied (nearly a third of all civilians killed were Soviet citizens, and more than 15% of all civilians killed in the war died in German extermination camps) and 10% were Axis.[10]

Many civilians died as a result of disease, starvation, massacres, genocide—in particular, the Holocaust—and aerial bombing. One estimate is that 12 million civilians died in Holocaust camps, 1.5 million by bombs, 7 million in Europe from other causes, and 7.5 million in China from other causes.[11] Allied civilian deaths totaled roughly 38 million, including 11.7 million in the Soviet Union, 7 million in China and 5.2 million from Poland. There were around 3 million civilian deaths on the Axis side, including 2 million in Germany and 0.6 million in Japan. The Holocaust refers to the organized state-sponsored murder of 6 million Jews, 1.8-1.9 million non-Jewish Poles, 200,000–800,000 Roma people, 200,000–300,000 people with disabilities, and other groups carried out by the Nazis during the war. The Soviet Union suffered by far the largest death toll of any nation in the war, over 23 million.
Mistreated, starved prisoners in the Ebensee concentration camp, Austria.
Mistreated, starved prisoners in the Ebensee concentration camp, Austria.

In addition to the Nazi concentration camps, the Soviet Gulag, or labor camps, led to the death of citizens of occupied countries such as Poland, Lithuania, Latvia, and Estonia, as well as German prisoners of war (POW) and even Soviet citizens themselves who had been supporters of the Nazis. Japanese POW camps also had high death rates; many were used as labour camps, and starvation conditions among the mainly U.S., British, Australian and other Commonwealth prisoners were little better than many German concentration camps. Sixty percent (1,238,000 ref. Krivosheev) of Soviet POWs died during the war. Vadim Erlikman puts it at 2.6 million Soviet POWs that died in German Captivity.[12] Richard Overy gives the number of 5.7 million Soviet POW and out of those 57% died or were killed.[13] Furthermore, 150,000 Japanese-Americans were interned by the U.S. and Canadian governments, as well as nearly 11,000 German and Italian residents of the U.S.
A survivor of German aerial bombardment, Siege of Warsaw.
A survivor of German aerial bombardment, Siege of Warsaw.

Despite the international treaties and a resolution adopted by the League of Nations on 14 May 1938 condemning the use of toxic gas by Japan, the Imperial Japanese Army frequently used chemical weapons. Because of fears of retaliation, however, those weapons were never used against Occidentals but only against other Orientals judged "inferior" by the imperial propaganda. According to historians Yoshiaki Yoshimi and Seiya Matsuno, the authorization for the use of chemical weapons was given by specific orders (rinsanmei) issued by Hirohito himself. For example, the Emperor authorized the use of toxic gas on 375 separate occasions during the invasion of Wuhan, from August to October 1938.

The bacteriological weapons were experimented on human beings by many units incorporated in the Japanese army, such as the infamous Unit 731, integrated by Imperial decree in the Kwantung army in 1936. Those weapons were mainly used in China and, according to some Japanese veterans, against Mongolians and Russian soldiers in 1939 during the Nomonhan incident.[14]

According to a joint study of historians featuring Zhifen Ju, Mark Peattie, Toru Kubo, and Mitsuyochi Himeta, more than 10 million Chinese were mobilized by the Japanese army and enslaved by the Kôa-in for slave labor in Manchukuo and north China.[15] According to Mitsuyoshi Himeta, at least 2.7 million died during the Sankō Sakusen operation implemented in Heipei and Shantung by General Yasuji Okamura.

From 1945 to 1951, German and Japanese officials and personnel were prosecuted for war crimes. Top German officials were tried at the Nuremberg Trials, and many Japanese officials at the Tokyo War Crime Trial and other war crimes trials in the Asia-Pacific region.

Resistance and collaboration

Main articles: Resistance during World War II and Collaboration during World War II

Members of the Dutch Eindhoven Resistance with troops of the U.S. 101st Airborne in front of the Eindhoven cathedral during Operation Market Garden in September 1944.
Members of the Dutch Eindhoven Resistance with troops of the U.S. 101st Airborne in front of the Eindhoven cathedral during Operation Market Garden in September 1944.

Resistance during World War II occurred in every occupied country by a variety of means, ranging from non-cooperation, disinformation, and propaganda to outright warfare.

Among the most notable resistance movements were the Polish Home Army, the French Maquis, the Yugoslav Partisans, the Greek resistance force, and the Italian Resistance in the German-occupied Northern Italy after 1943. Germany itself also had an anti-Nazi movement. The Communist resistance was among the fiercest, since they were already organised and militant even before the war and they were ideologically opposed to the Nazis.

Before D-Day, there were some operations performed by the French Resistance to help with the forthcoming invasion. Communications lines were cut; trains were derailed; roads, water towers, and ammunition depots were destroyed; and some German garrisons were attacked.

There were also resistance movements fighting against the Allied invaders. The German resistance petered out within a few years, while in the Baltic states resistance operations against the occupation continued into the 1960s.

Home fronts
During the war, women worked in factories throughout much of the West and East.
During the war, women worked in factories throughout much of the West and East.

Main article: Home front during World War II

"Home front" is the name given to the activities of the civilians of the nations at war. All the main countries reorganized their homefronts to produce munitions and soldiers, with 40–60% of GDP being devoted to the war effort. Women were drafted in the Soviet Union and Britain. Shortages were everywhere, and severe food shortages caused malnutrition and even starvation, such as in the Netherlands and in Leningrad. New workers were recruited, especially housewives, the unemployed, students, and retired people. Skilled jobs were re-engineered and simplified ("de-skilling") so that unskilled workers could handle them. Every major nation imposed censorship on the media as well as a propaganda program designed to boost the war effort and stifle negative rumors. Every major country imposed a system of rationing and price controls. Black markets flourished in areas controlled by Germany. Germany brought in millions of prisoners of war, slave laborers, and forced workers to staff its munitions factories. Many were killed in the bombing raids, the rest became refugees as the war ended.

Technology
German Enigma machine for encryption.
German Enigma machine for encryption.

Main articles: Technology during World War II and Technological escalation during World War II

Weapons and technology improved rapidly during World War II and some of these played a crucial role in determining the outcome of the war. Many major technologies were used for the first time, including nuclear weapons, radar, proximity fuses, jet engines, ballistic missiles, and data-processing analog devices (primitive computers). Every year, the piston engines were improved. Enormous advances were made in aircraft, submarine, and tank designs, such that models coming into use at the beginning of the war were long obsolete by its end. One entirely new kind of ship was the amphibious landing craft.

Industrial production played a role in the Allied victory. The Allies more effectively mobilized their economies and drew from a larger economic base. The peak year of munitions production was 1944, with the Allies out-producing the Axis by a ratio of 3 to 1. (Germany produced 19% and Japan 7% of the world's munitions; the U.S. produced 47%, Britain and Canada 14%, and the Soviets 11%).[16]

The Allies used low-cost mass production techniques, using standardized models. Japan and Germany continued to rely on expensive hand-crafted methods. Japan thus produced hundreds of airplane designs and did not reach mass-production efficiency; the new models were only slightly better than the original 1940 planes, while the Allies rapidly advanced in technology.[17] Germany thus spent heavily on high-tech weaponry, including the V-1 flying bomb and V-2 rocket, advanced submarines, jet engines, and heavy tanks that proved strategically of minor value. The combination of better logistics and mass production proved crucial in the victory. "The Allies did not depend on simple numbers for victory but on the quality of their technology and the fighting effectiveness of their forces... In both Germany and Japan less emphasis was placed upon the non-combat areas of war: procurement, logistics, military services," concludes historian Richard Overy.[18]

Delivery of weapons to the battlefront was a matter of logistics. The Allies again did a much better job in moving munitions from factories to the front lines. A large fraction of the German tanks after June 1944 never reached the battlefield, and those that did often ran short of fuel. Japan in particular was notably inefficient in its logistics system.[19]

Many new medical and surgical techniques were employed as well as new drugs like sulfa and penicillin, not to mention serious advances in biological warfare and nerve gases. The Japanese control of the quinine supply forced the Australians to invent new anti-malarial drugs. The saline bath was invented to treat burns. More prompt application of sulfa drugs saved countless lives. New local anesthetics were introduced making possible surgery close to the front lines. The Americans discovered that only 20% of wounds were cause by machine-gun or rifle bullets (compared to 35% in World War I). Most came from high explosive shells and fragments, which besides the direct wound caused shock from their blast effects. Most deaths came from shock and blood loss, which were countered by a major innovation, blood transfusions.[20]

Cryptography played an important part in the war, as the United States had broken the Japanese naval codes and knew the Japanese plan of attack at Midway. British and Polish codebreakers deciphered several German codes, giving the Allies an advantage in the European theater as well.

The massive research and development demands of the war accelerated the growth of the scientific communities in Allied states, while German and Japanese laboratories were disbanded; many German engineers and scientists continued their weapons research after the war in the United States, the Soviet Union and other countries.

See also: Military production during World War II and List of World War II military equipment


Aftermath
Germany's territorial losses 1919–1945
Germany's territorial losses 1919–1945

Main articles: Aftermath of World War II and Effects of World War II

The war concluded with the surrender and occupation of Germany and Japan. It left behind millions of displaced persons and prisoners of war, and resulted in many new international boundaries. The economies of Europe, China and Japan were largely destroyed as a result of the war. In 1947, U.S. Secretary of State George Marshall devised the "European Recovery Program", better known as the Marshall Plan. Effective from 1948 to 1952, it allocated 13 billion dollars for the reconstruction of Western Europe. To prevent (or at least minimize) future conflicts, the allied nations, led by the United States, formed the United Nations in San Francisco, California in 1945. One of the first actions of the United Nations was the creation of the State of Israel, partly in response to the Holocaust.

Aftermath of World War II in Europe

Main articles: Marshall Plan, Eastern bloc, Iron Curtain, Expulsion of Germans after World War II, Allied Occupation Zones in Germany, Morgenthau plan, and Oder-Neisse line

German occupation zones in 1946 after territorial annexations in the East. The Saarland (in the French zone) is shown with stripes because it was removed from Germany by France in 1947 as a protectorate, and was not incorporated into the Federal Republic of Germany until 1957.
German occupation zones in 1946 after territorial annexations in the East. The Saarland (in the French zone) is shown with stripes because it was removed from Germany by France in 1947 as a protectorate, and was not incorporated into the Federal Republic of Germany until 1957.

The end of the war hastened the independence of many British crown colonies (such as India) and Dutch territories (such as Indonesia) and the formation of new nations and alliances throughout Asia and Africa. The Philippines were granted their independence in 1946 as previously promised by the United States. Poland's boundaries were re-drawn to include portions of pre-war Germany, including East Prussia and Upper Silesia, while ceding most of the areas taken by the Soviet Union in the Molotov-Ribbentrop partition of 1939, effectively moving Poland to the west. Germany was split into four zones of occupation, and the three zones under the Western Allies was reconstituted as a constitutional democracy. The Soviet Union's influence increased as they established hegemony over most of eastern Europe, and incorporated parts of Finland and Poland into their new boundaries. Europe was informally split into Western and Soviet spheres of influence, which heightened existing tensions between the two camps and helped establish the Cold War.

Germany was partitioned into four zones of occupation, coordinated by the Allied Control Council. The American, British, and French zones joined in 1949 as the Federal Republic of Germany, and the Soviet zone became the German Democratic Republic. In Germany, economic suppression and denazification took place. Millions of Germans and Poles were expelled from their homelands as a result of the territorial annexations in Eastern Europe agreed upon at the Yalta and Potsdam conferences. In the West, Alsace-Lorraine was given to France, which also separated the Saar area from Germany. Austria was separated from Germany and divided into four zones of occupation, which were united in 1955 to become the Republic of Austria. The Soviet Union occupied much of Central and Eastern Europe and the Balkans. In all the USSR-occupied countries, with the exception of Austria, the Soviet Union helped Communist regimes to power. It also annexed the Baltic countries Estonia, Latvia, and Lithuania.

Aftermath of World War II in Asia

Main articles: Occupied Japan, Division of Korea, and Chinese Civil War

In Asia, the Japanese Empire's government was dismantled under General Douglas MacArthur and replaced by a constitutional monarchy with the emperor as a figurehead. The Korean peninsula was divided into two zones administered by Soviet and American forces. The war greatly enhanced China's international prestige but severely weakened Chiang Kai-shek's central government and the armed forces of the Republic of China. Partly because of this, in the subsequent Chinese Civil War, the Chinese Nationalists lost and were forced to retreat to Taiwan, while the Chinese Communists established the People's Republic of China on the mainland in 1949.

Japan was occupied by the U.S, aided by Commonwealth troops, until the peace treaty took effect in 1952. The defeat of Japan also lead to the establishment of the Far eastern commission which set out policies for Japan to fulfill under the terms of surrender. In accordance with the Yalta Conference agreements, the Soviet Union occupied and subsequently annexed Sakhalin and the Kuril islands. Korea was divided between the U.S. and the Soviet Union, leading to the creation of two separate governments in 1948. The war was a pivotal point in China's history. Before the war against Japan, China had suffered nearly a century of humiliation at the hands of various imperialist powers and was relegated to a semi-colonial status. However, the war greatly enhanced China's international status. Not only was the central government under Chiang Kai-shek able to abrogate most of the unequal treaties China had signed in the past century, the Republic of China also became a founding member of the United Nations and a permanent member in the Security Council. China also reclaimed Manchuria and Taiwan. Nevertheless, eight years of war greatly taxed the central government, and many of its nation-building measures adopted since it came to power in 1928 were disrupted by the war. Communist activities also expanded greatly in occupied areas, making post-war administration of these areas difficult. Vast war damages and hyperinflation thereafter greatly demoralized the populace, along with the continuation of the Chinese Civil War between the Kuomintang and the Communists. Partly because of the severe blow his army and government had suffered during the war against Japan, the Kuomintang, along with state apparatus of the Republic of China, retreated to Taiwan in 1949 and in its place the Chinese communists established the People's Republic of China on the mainland.

Media

Main article: World War II in contemporary culture

The term most used in the United Kingdom and Canada is "Second World War", while American publishers use the term "World War II". Thus the Oxford University Press uses The Oxford Companion to the Second World War in the United Kingdom, and The Oxford Companion to World War II for the identical 1995 book in the United States.

The OED reports the first use of "Second World War" was by novelist H.G. Wells in 1930, although it may well have been used earlier.[21] The term was immediately used when war was declared; for example, the September 3, 1939, issue of the Canadian newspaper, The Calgary Herald. Prior the United States' entry into the War, many Americans referred to it as the "European War".

World War II has been portrayed in numerous media in many languages. The hundreds of fictional (versus documentary) war movies include Twelve O'Clock High (1949), The Bridge on the River Kwai (1957), The Dirty Dozen (1967), Patton (1970), Das Boot (1981), Saving Private Ryan (1998) and Pearl Harbor (2001). The war figures prominently in thousands of written works, including Joseph Heller's Catch-22, Akiyuki Nosaka's Grave of the Fireflies, Anne Frank's The Diary of a Young Girl and Kurt Vonnegut's Slaughterhouse-Five. Games set within World War II include the board game Axis and Allies and video games 1942 (1984), Wolfenstein 3D (1992), and Call of Duty (2003). The war has been portrayed in many television media, such as Hogan's Heroes (1965–1971) and the miniseries Band of Brothers (2001).