World War II
"The Second World War", "WWII", and "WW2" redirect here.
World War II (WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945.
In a state of total war, directly involving more than 100 million personnel from more than 30 countries, the major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources.
Following the onset of campaigns in North Africa and East Africa, and the fall of France in mid-1940, the war continued primarily between the European Axis powers and the British Empire, with war in the Balkans, the aerial Battle of Britain, the Blitz, and the Battle of the Atlantic.
On 22 June 1941, Germany led the European Axis powers in an invasion of the Soviet Union, opening the largest land theatre of war in history and trapping the Axis, crucially the German Wehrmacht, in a war of attrition.
In December 1941, Japan attacked American and British territories with near-simultaneous offensives against Southeast Asia and the Central Pacific including an attack on the US fleet at Pearl Harbor.
Following a US declaration of war against Japan, which followed one from the UK, the European Axis powers declared war on the United States in solidarity with their ally.
Japan soon captured much of the Western Pacific, but its advances were halted in 1942 after losing the critical Battle of Midway; later, Germany and Italy were defeated in North Africa and at Stalingrad in the Soviet Union.
Key setbacks in 1943—including a series of German defeats on the Eastern Front, the Allied invasions of Sicily and the Italian mainland, and Allied offensives in the Pacific—cost the Axis its initiative and forced it into strategic retreat on all fronts.
During 1944 and 1945, Japan suffered reversals in mainland Asia, while the Allies crippled the Japanese Navy and captured key Western Pacific islands.
The war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union, culminating in the capture of Berlin by Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.
Following the Potsdam Declaration by the Allies on 26 July 1945 and the refusal of Japan to surrender on its terms, the United States dropped the first atomic bombs on the Japanese cities of Hiroshima, on 6 August 1945, and Nagasaki, on 9 August.
Faced with an imminent invasion of the Japanese archipelago, the possibility of additional atomic bombings, and the Soviet entry into the war against Japan and its invasion of Manchuria on 9 August, Japan announced its intention to surrender on 15 August 1945, cementing total victory in Asia for the Allies.
Despite their well documented war crimes, mainly perpetrated in Greece and Yugoslavia, Italian leaders and generals were often pardoned, thanks to diplomatic activities.
World War II changed the political alignment and social structure of the globe.
The United Nations (UN) was established to foster international co-operation and prevent future conflicts, and the victorious great powers—China, France, the Soviet Union, the United Kingdom, and the United States—became the permanent members of its Security Council.
Most countries whose industries had been damaged moved towards economic recovery and expansion.
Political integration, especially in Europe, began as an effort to forestall future hostilities, end pre-war enmities and forge a sense of common identity.
See also: Timeline of World War II
The war in Europe is generally considered to have started on 1 September 1939, beginning with the German invasion of Poland; the United Kingdom and France declared war on Germany two days later.
Others follow the British historian A. , who held that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously, and the two wars merged in 1941. J. P. Taylor
This article uses the conventional dating.
Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935.
The exact date of the war's end is also not universally agreed upon.
It was generally accepted at the time that the war ended with the armistice of 14 August 1945 (V-J Day), rather than with the formal surrender of Japan on 2 September 1945, which officially ended the war in Asia.
A peace treaty between Japan and the Allies was signed in 1951.
No formal peace treaty between Japan and the Soviet Union was ever signed.
Main article: Causes of World War II
World War I had radically altered the political European map, with the defeat of the Central Powers—including Austria-Hungary, Germany, Bulgaria and the Ottoman Empire—and the 1917 Bolshevik seizure of power in Russia, which led to the founding of the Soviet Union.
Meanwhile, the victorious Allies of World War I, such as France, Belgium, Italy, Romania, and Greece, gained territory, and new nation-states were created out of the collapse of Austria-Hungary and the Ottoman and Russian Empires.
The organisation's primary goals were to prevent armed conflict through collective security, military and naval disarmament, and settling international disputes through peaceful negotiations and arbitration.
These sentiments were especially marked in Germany because of the significant territorial, colonial, and financial losses imposed by the Treaty of Versailles.
Under the treaty, Germany lost around 13 percent of its home territory and all its overseas possessions, while German annexation of other states was prohibited, reparations were imposed, and limits were placed on the size and capability of the country's armed forces.
Italy, as an Entente ally, had made some post-war territorial gains; however, Italian nationalists were angered that the promises made by the United Kingdom and France to secure Italian entrance into the war were not fulfilled in the peace settlement.
From 1922 to 1925, the Fascist movement led by Benito Mussolini seized power in Italy with a nationalist, totalitarian, and class collaborationist agenda that abolished representative democracy, repressed socialist, left-wing and liberal forces, and pursued an aggressive expansionist foreign policy aimed at making Italy a world power, and promising the creation of a "New Roman Empire".
Adolf Hitler, after an unsuccessful attempt to overthrow the German government in 1923, eventually became the Chancellor of Germany in 1933.
He abolished democracy, espousing a radical, racially motivated revision of the world order, and soon began a massive rearmament campaign.
Meanwhile, France, to secure its alliance, allowed Italy a free hand in Ethiopia, which Italy desired as a colonial possession.
The situation was aggravated in early 1935 when the Territory of the Saar Basin was legally reunited with Germany, and Hitler repudiated the Treaty of Versailles, accelerated his rearmament programme, and introduced conscription.
The United Kingdom, France and Italy formed the Stresa Front in April 1935 in order to contain Germany, a key step towards military globalisation; however, that June, the United Kingdom made an independent naval agreement with Germany, easing prior restrictions.
The Soviet Union, concerned by Germany's goals of capturing vast areas of Eastern Europe, drafted a treaty of mutual assistance with France.
Before taking effect, though, the Franco-Soviet pact was required to go through the bureaucracy of the League of Nations, which rendered it essentially toothless.
The United States, concerned with events in Europe and Asia, passed the Neutrality Act in August of the same year.
In October 1936, Germany and Italy formed the Rome–Berlin Axis.
A month later, Germany and Japan signed the Anti-Comintern Pact, which Italy joined the following year.
The Kuomintang (KMT) party in China launched a unification campaign against regional warlords and nominally unified China in the mid-1920s, but was soon embroiled in a civil war against its former Chinese Communist Party allies and new regional warlords.
In 1931, an increasingly militaristic Empire of Japan, which had long sought influence in China as the first step of what its government saw as the country's right to rule Asia, staged the Mukden Incident as a pretext to invade Manchuria and establish the puppet state of Manchukuo.
China appealed to the League of Nations to stop the Japanese invasion of Manchuria.
Japan withdrew from the League of Nations after being condemned for its incursion into Manchuria.
Italian invasion of Ethiopia (1935)
Main article: Second Italo-Ethiopian War
The war resulted in the military occupation of Ethiopia and its annexation into the newly created colony of Italian East Africa (Africa Orientale Italiana, or AOI); in addition it exposed the weakness of the League of Nations as a force to preserve peace.
The United Kingdom and France supported imposing sanctions on Italy for the invasion, but the sanctions were not fully enforced and failed to end the Italian invasion.
Italy subsequently dropped its objections to Germany's goal of absorbing Austria.
Spanish Civil War (1936–1939)
Main article: Spanish Civil War
Italy supported the Nationalists to a greater extent than the Nazis did: altogether Mussolini sent to Spain more than 70,000 ground troops and 6,000 aviation personnel, as well as about 720 aircraft.
The Soviet Union supported the existing government, the Spanish Republic.
More than 30,000 foreign volunteers, known as the International Brigades, also fought against the Nationalists.
Both Germany and the Soviet Union used this proxy war as an opportunity to test in combat their most advanced weapons and tactics.
The Nationalists won the civil war in April 1939; Franco, now dictator, remained officially neutral during World War II but generally favoured the Axis.
Japanese invasion of China (1937)
Main article: Second Sino-Japanese War
The Japanese continued to push the Chinese forces back, capturing the capital Nanking in December 1937.
After the fall of Nanking, tens or hundreds of thousands of Chinese civilians and disarmed combatants were murdered by the Japanese.
In June 1938, Chinese forces stalled the Japanese advance by flooding the Yellow River; this manoeuvre bought time for the Chinese to prepare their defences at Wuhan, but the city was taken by October.
Japanese military victories did not bring about the collapse of Chinese resistance that Japan had hoped to achieve; instead, the Chinese government relocated inland to Chongqing and continued the war.
Soviet–Japanese border conflicts
Main article: Soviet–Japanese border conflicts
The Japanese doctrine of Hokushin-ron, which emphasised Japan's expansion northward, was favoured by the Imperial Army during this time.
With the Japanese defeat at Khalkin Gol in 1939, the ongoing Second Sino-Japanese War and ally Nazi Germany pursuing neutrality with the Soviets, this policy would prove difficult to maintain.
Japan and the Soviet Union eventually signed a Neutrality Pact in April 1941, and Japan adopted the doctrine of Nanshin-ron, promoted by the Navy, which took its focus southward, eventually leading to its war with the United States and the Western Allies.
European occupations and agreements
In Europe, Germany and Italy were becoming more aggressive.
Soon the United Kingdom and France followed the appeasement policy of British Prime Minister Neville Chamberlain and conceded this territory to Germany in the Munich Agreement, which was made against the wishes of the Czechoslovak government, in exchange for a promise of no further territorial demands.
Although all of Germany's stated demands had been satisfied by the agreement, privately Hitler was furious that British interference had prevented him from seizing all of Czechoslovakia in one operation.
In subsequent speeches Hitler attacked British and Jewish "war-mongers" and in January 1939 secretly ordered a major build-up of the German navy to challenge British naval supremacy.
Greatly alarmed and with Hitler making further demands on the Free City of Danzig, the United Kingdom and France guaranteed their support for Polish independence; when Italy conquered Albania in April 1939, the same guarantee was extended to the Kingdom of Romania and Greece.
The situation reached a general crisis in late August as German troops continued to mobilise against the Polish border.
On 23 August, when tripartite negotiations about a military alliance between France, the United Kingdom and Soviet Union stalled, the Soviet Union signed a non-aggression pact with Germany.
This pact had a secret protocol that defined German and Soviet "spheres of influence" (western Poland and Lithuania for Germany; eastern Poland, Finland, Estonia, Latvia and Bessarabia for the Soviet Union), and raised the question of continuing Polish independence.
The pact neutralised the possibility of Soviet opposition to a campaign against Poland, and assured that Germany would not have to face the prospect of a two-front war, as it had in World War I.
Immediately after that, Hitler ordered the attack to proceed on 26 August, but upon hearing that the United Kingdom had concluded a formal mutual assistance pact with Poland, and that Italy would maintain neutrality, he decided to delay it.
In response to British requests for direct negotiations to avoid war, Germany made demands on Poland, which only served as a pretext to worsen relations.
On 29 August, Hitler demanded that a Polish plenipotentiary immediately travel to Berlin to negotiate the handover of Danzig, and to allow a plebiscite in the Polish Corridor in which the German minority would vote on secession.
The Poles refused to comply with the German demands, and on the night of 30–31 August in a stormy meeting with the British ambassador Nevile Henderson, Ribbentrop declared that Germany considered its claims rejected.
Course of the war
Further information: Diplomatic history of World War II
War breaks out in Europe (1939–40)
Main article: European theatre of World War II
The first German attack of the war came against the Polish defenses at Westerplatte.
The United Kingdom responded with an ultimatum to Germany to cease military operations, and on 3 September, after the ultimatum was ignored, France and Britain declared war on Germany, followed by Australia, New Zealand, South Africa and Canada.
The Western Allies also began a naval blockade of Germany, which aimed to damage the country's economy and the war effort.
On 8 September, German troops reached the suburbs of Warsaw.
Remnants of the Polish army broke through to besieged Warsaw.
On 27 September, the Warsaw garrison surrendered to the Germans, and the last large operational unit of the Polish Army surrendered on 6 October.
On 6 October, Hitler made a public peace overture to the United Kingdom and France but said that the future of Poland was to be determined exclusively by Germany and the Soviet Union.
The proposal was rejected, and Hitler ordered an immediate offensive against France, which was postponed until the spring of 1940 due to bad weather.
The Soviet Union forced the Baltic countries—Estonia, Latvia and Lithuania, which were in the Soviet "sphere of influence" under the Molotov-Ribbentrop pact—to sign "mutual assistance pacts" that stipulated stationing Soviet troops in these countries.
Soon after, significant Soviet military contingents were moved there.
Finland refused to sign a similar pact and rejected ceding part of its territory to the Soviet Union.
The Soviet Union invaded Finland in November 1939, and the Soviet Union was expelled from the League of Nations.
Meanwhile, Nazi-Soviet political rapprochement and economic co-operation gradually stalled, and both states began preparations for war.
Western Europe (1940–41)
Main article: Western Front (World War II)
Denmark capitulated after a few hours, and Norway was conquered within two months despite Allied support.
On the same day, Germany launched an offensive against France.
The Germans carried out a flanking manoeuvre through the Ardennes region, which was mistakenly perceived by Allies as an impenetrable natural barrier against armoured vehicles.
By successfully implementing new blitzkrieg tactics, the Wehrmacht rapidly advanced to the Channel and cut off the Allied forces in Belgium, trapping the bulk of the Allied armies in a cauldron on the Franco-Belgian border near Lille.
The United Kingdom was able to evacuate a significant number of Allied troops from the continent by early June, although abandoning almost all their equipment.
On 10 June, Italy invaded France, declaring war on both France and the United Kingdom.
The Germans turned south against the weakened French army, and Paris fell to them on 14 June.
Eight days later France signed an armistice with Germany; it was divided into German and Italian occupation zones, and an unoccupied rump state under the Vichy Regime, which, though officially neutral, was generally aligned with Germany.
France kept its fleet, which the United Kingdom attacked on 3 July in an attempt to prevent its seizure by Germany.
The United Kingdom rejected Hitler's ultimatum, and the German air superiority campaign started in August but failed to defeat RAF Fighter Command, forcing the indefinite postponement of the proposed German invasion of Britain.
The German strategic bombing offensive intensified with night attacks on London and other cities in the Blitz, but failed to significantly disrupt the British war effort and largely ended in May 1941.
In September the United States further agreed to a trade of American destroyers for British bases.
Still, a large majority of the American public continued to oppose any direct military intervention in the conflict well into 1941.
In December 1940 Roosevelt accused Hitler of planning world conquest and ruled out any negotiations as useless, calling for the United States to become an "arsenal of democracy" and promoting Lend-Lease programmes of aid to support the British war effort.
The United States started strategic planning to prepare for a full-scale offensive against Germany.
The Tripartite Pact stipulated that any country, with the exception of the Soviet Union, which attacked any Axis Power would be forced to go to war against all three.
The Axis expanded in November 1940 when Hungary, Slovakia and Romania joined.
Main article: Mediterranean and Middle East theatre of World War II
In early June 1940, the Italian Regia Aeronautica attacked and besieged Malta, a British possession.
In October, Italy attacked Greece, but the attack was repulsed with heavy Italian casualties; the campaign ended within months with minor territorial changes.
Germany started preparation for an invasion of the Balkans to assist Italy, to prevent the British from gaining a foothold there, which would be a potential threat for Romanian oil fields, and to strike against the British dominance of the Mediterranean.
The offensives were highly successful; by early February 1941, Italy had lost control of eastern Libya and large numbers of Italian troops had been taken prisoner.
The Italian Navy also suffered significant defeats, with the Royal Navy putting three Italian battleships out of commission by means of a carrier attack at Taranto, and neutralising several more warships at the Battle of Cape Matapan.
In under a month, Axis forces advanced to western Egypt and besieged the port of Tobruk.
The airborne invasion of the Greek island of Crete at the end of May completed the German conquest of the Balkans.
Although the Axis victory was swift, bitter and large-scale partisan warfare subsequently broke out against the Axis occupation of Yugoslavia, which continued until the end of the war.
Between June and July, they invaded and occupied the French possessions Syria and Lebanon, with the assistance of the Free French.
Axis attack on the Soviet Union (1941)
Main article: Eastern Front (World War II)
With the situation in Europe and Asia relatively stable, Germany, Japan, and the Soviet Union made preparations.
With the Soviets wary of mounting tensions with Germany and the Japanese planning to take advantage of the European War by seizing resource-rich European possessions in Southeast Asia, the two powers signed the Soviet–Japanese Neutrality Pact in April 1941.
By contrast, the Germans were steadily making preparations for an attack on the Soviet Union, massing forces on the Soviet border.
Hitler believed that the United Kingdom's refusal to end the war was based on the hope that the United States and the Soviet Union would enter the war against Germany sooner or later.
He, therefore, decided to try to strengthen Germany's relations with the Soviets, or failing that to attack and eliminate them as a factor.
In November 1940, negotiations took place to determine if the Soviet Union would join the Tripartite Pact.
The Soviets showed some interest but asked for concessions from Finland, Bulgaria, Turkey, and Japan that Germany considered unacceptable.
On 18 December 1940, Hitler issued the directive to prepare for an invasion of the Soviet Union.
On 22 June 1941, Germany, supported by Italy and Romania, invaded the Soviet Union in Operation Barbarossa, with Germany accusing the Soviets of plotting against them.
They were joined shortly by Finland and Hungary.
The primary targets of this surprise offensive were the Baltic region, Moscow and Ukraine, with the ultimate goal of ending the 1941 campaign near the Arkhangelsk-Astrakhan line, from the Caspian to the White Seas.
Hitler's objectives were to eliminate the Soviet Union as a military power, exterminate Communism, generate Lebensraum ("living space") by dispossessing the native population and guarantee access to the strategic resources needed to defeat Germany's remaining rivals.
During the summer, the Axis made significant gains into Soviet territory, inflicting immense losses in both personnel and materiel.
By mid-August, however, the German Army High Command decided to suspend the offensive of a considerably depleted Army Group Centre, and to divert the 2nd Panzer Group to reinforce troops advancing towards central Ukraine and Leningrad.
The Kiev offensive was overwhelmingly successful, resulting in encirclement and elimination of four Soviet armies, and made possible further advance into Crimea and industrially developed Eastern Ukraine (the First Battle of Kharkov).
The diversion of three quarters of the Axis troops and the majority of their air forces from France and the central Mediterranean to the Eastern Front prompted the United Kingdom to reconsider its grand strategy.
In July, the UK and the Soviet Union formed a military alliance against Germany and in August, the United Kingdom and the United States jointly issued the Atlantic Charter, which outlined British and American goals for the postwar world.
A major offensive against Moscow was renewed; after two months of fierce battles in increasingly harsh weather, the German army almost reached the outer suburbs of Moscow, where the exhausted troops were forced to suspend their offensive.
Large territorial gains were made by Axis forces, but their campaign had failed to achieve its main objectives: two key cities remained in Soviet hands, the Soviet capability to resist was not broken, and the Soviet Union retained a considerable part of its military potential.
The blitzkrieg phase of the war in Europe had ended.
By early December, freshly mobilised reserves allowed the Soviets to achieve numerical parity with Axis troops.
This, as well as intelligence data which established that a minimal number of Soviet troops in the East would be sufficient to deter any attack by the Japanese Kwantung Army, allowed the Soviets to begin a massive counter-offensive that started on 5 December all along the front and pushed German troops 100–250 kilometres (62–155 mi) west.
War breaks out in the Pacific (1941)
Main article: Pacific War
In 1939, the United States notified Japan that it would not be extending its trade treaty and American public opinion opposing Japanese expansionism led to a series of economic sanctions, the Export Control Acts, which banned U.S. exports of chemicals, minerals and military parts to Japan and increased economic pressure on the Japanese regime.
During 1939 Japan launched its first attack against Changsha, a strategically important Chinese city, but was repulsed by late September.
Despite several offensives by both sides, the war between China and Japan was stalemated by 1940.
To increase pressure on China by blocking supply routes, and to better position Japanese forces in the event of a war with the Western powers, Japan invaded and occupied northern Indochina in September, 1940.
Chinese nationalist forces launched a large-scale counter-offensive in early 1940.
The continued antipathy between Chinese communist and nationalist forces culminated in armed clashes in January 1941, effectively ending their co-operation.
In March, the Japanese 11th army attacked the headquarters of the Chinese 19th army but was repulsed during Battle of Shanggao.
In September, Japan attempted to take the city of Changsha again and clashed with Chinese nationalist forces.
German successes in Europe encouraged Japan to increase pressure on European governments in Southeast Asia.
The Dutch government agreed to provide Japan some oil supplies from the Dutch East Indies, but negotiations for additional access to their resources ended in failure in June 1941.
In July 1941 Japan sent troops to southern Indochina, thus threatening British and Dutch possessions in the Far East.
The United States, United Kingdom, and other Western governments reacted to this move with a freeze on Japanese assets and a total oil embargo.
At the same time, Japan was planning an invasion of the Soviet Far East, intending to capitalise off the German invasion in the west, but abandoned the operation after the sanctions.
Since early 1941 the United States and Japan had been engaged in negotiations in an attempt to improve their strained relations and end the war in China.
During these negotiations, Japan advanced a number of proposals which were dismissed by the Americans as inadequate.
At the same time the United States, the United Kingdom, and the Netherlands engaged in secret discussions for the joint defence of their territories, in the event of a Japanese attack against any of them.
Roosevelt reinforced the Philippines (an American protectorate scheduled for independence in 1946) and warned Japan that the United States would react to Japanese attacks against any "neighboring countries".
Frustrated at the lack of progress and feeling the pinch of the American–British–Dutch sanctions, Japan prepared for war.
On 20 November, a new government under Hideki Tojo presented an interim proposal as its final offer.
It called for the end of American aid to China and for lifting the embargo on the supply of oil and other resources to Japan.
In exchange, Japan promised not to launch any attacks in Southeast Asia and to withdraw its forces from southern Indochina.
The American counter-proposal of 26 November required that Japan evacuate all of China without conditions and conclude non-aggression pacts with all Pacific powers.
That meant Japan was essentially forced to choose between abandoning its ambitions in China, or seizing the natural resources it needed in the Dutch East Indies by force; the Japanese military did not consider the former an option, and many officers considered the oil embargo an unspoken declaration of war.
Japan planned to rapidly seize European colonies in Asia to create a large defensive perimeter stretching into the Central Pacific.
The Japanese would then be free to exploit the resources of Southeast Asia while exhausting the over-stretched Allies by fighting a defensive war.
To prevent American intervention while securing the perimeter, it was further planned to neutralise the United States Pacific Fleet and the American military presence in the Philippines from the outset.
On 7 December 1941 (8 December in Asian time zones), Japan attacked British and American holdings with near-simultaneous offensives against Southeast Asia and the Central Pacific.
The Japanese invasion of Thailand led to Thailand's decision to ally itself with Japan and the other Japanese attacks led the United States, United Kingdom, China, Australia, and several other states to formally declare war on Japan, whereas the Soviet Union, being heavily involved in large-scale hostilities with European Axis countries, maintained its neutrality agreement with Japan.
Germany, followed by the other Axis states, declared war on the United States in solidarity with Japan, citing as justification the American attacks on German war vessels that had been ordered by Roosevelt.
Axis advance stalls (1942–43)
On 1 January 1942, the Allied Big Four—the Soviet Union, China, the United Kingdom and the United States—and 22 smaller or exiled governments issued the Declaration by United Nations, thereby affirming the Atlantic Charter, and agreeing not to sign a separate peace with the Axis powers.
During 1942, Allied officials debated on the appropriate grand strategy to pursue.
All agreed that defeating Germany was the primary objective.
The Americans favoured a straightforward, large-scale attack on Germany through France.
The Soviets were also demanding a second front.
The British, on the other hand, argued that military operations should target peripheral areas to wear out German strength, leading to increasing demoralisation, and bolster resistance forces.
Germany itself would be subject to a heavy bombing campaign.
An offensive against Germany would then be launched primarily by Allied armour without using large-scale armies.
Eventually, the British persuaded the Americans that a landing in France was infeasible in 1942 and they should instead focus on driving the Axis out of North Africa.
The British and Americans agreed to continue to press the initiative in the Mediterranean by invading Sicily to fully secure the Mediterranean supply routes.
Although the British argued for further operations in the Balkans to bring Turkey into the war, in May 1943, the Americans extracted a British commitment to limit Allied operations in the Mediterranean to an invasion of the Italian mainland and to invade France in 1944.
By the end of April 1942, Japan and its ally Thailand had almost fully conquered Burma, Malaya, the Dutch East Indies, Singapore, and Rabaul, inflicting severe losses on Allied troops and taking a large number of prisoners.
On 16 April, in Burma, 7,000 British soldiers were encircled by the Japanese 33rd Division during the Battle of Yenangyaung and rescued by the Chinese 38th Division.
In January 1942, the only Allied success against Japan was a Chinese victory at Changsha.
These easy victories over the unprepared US and European opponents left Japan overconfident, as well as overextended.
The planned invasion was thwarted when an Allied task force, centred on two American fleet carriers, fought Japanese naval forces to a draw in the Battle of the Coral Sea.
Japan's next plan, motivated by the earlier Doolittle Raid, was to seize Midway Atoll and lure American carriers into battle to be eliminated; as a diversion, Japan would also send forces to occupy the Aleutian Islands in Alaska.
In mid-May, Japan started the Zhejiang-Jiangxi campaign in China, with the goal of inflicting retribution on the Chinese who aided the surviving American airmen in the Doolittle Raid by destroying air bases and fighting against the Chinese 23rd and 32nd Army Groups.
In early June, Japan put its operations into action, but the Americans, having broken Japanese naval codes in late May, were fully aware of the plans and order of battle, and used this knowledge to achieve a decisive victory at Midway over the Imperial Japanese Navy.
With its capacity for aggressive action greatly diminished as a result of the Midway battle, Japan chose to focus on a belated attempt to capture Port Moresby by an overland campaign in the Territory of Papua.
The Americans planned a counter-attack against Japanese positions in the southern Solomon Islands, primarily Guadalcanal, as a first step towards capturing Rabaul, the main Japanese base in Southeast Asia.
Both plans started in July, but by mid-September, the Battle for Guadalcanal took priority for the Japanese, and troops in New Guinea were ordered to withdraw from the Port Moresby area to the northern part of the island, where they faced Australian and United States troops in the Battle of Buna–Gona.
Guadalcanal soon became a focal point for both sides with heavy commitments of troops and ships in the battle for Guadalcanal.
By the start of 1943, the Japanese were defeated on the island and withdrew their troops.
In Burma, Commonwealth forces mounted two operations.
The first, an offensive into the Arakan region in late 1942, went disastrously, forcing a retreat back to India by May 1943.
The second was the insertion of irregular forces behind Japanese front-lines in February which, by the end of April, had achieved mixed results.
Eastern Front (1942–43)
Despite considerable losses, in early 1942 Germany and its allies stopped a major Soviet offensive in central and southern Russia, keeping most territorial gains they had achieved during the previous year.
In May the Germans defeated Soviet offensives in the Kerch Peninsula and at Kharkov, and then launched their main summer offensive against southern Russia in June 1942, to seize the oil fields of the Caucasus and occupy the Kuban steppe, while maintaining positions on the northern and central areas of the front.
The Soviets decided to make their stand at Stalingrad on the Volga.
The Soviets began their second winter counter-offensive, starting with an encirclement of German forces at Stalingrad, and an assault on the Rzhev salient near Moscow, though the latter failed disastrously.
By early February 1943, the German Army had taken tremendous losses; German troops at Stalingrad had been defeated, and the front-line had been pushed back beyond its position before the summer offensive.
Western Europe/Atlantic and Mediterranean (1942–43)
Exploiting poor American naval command decisions, the German navy ravaged Allied shipping off the American Atlantic coast.
By November 1941, Commonwealth forces had launched a counter-offensive, Operation Crusader, in North Africa, and reclaimed all the gains the Germans and Italians had made.
In North Africa, the Germans launched an offensive in January, pushing the British back to positions at the Gazala line by early February, followed by a temporary lull in combat which Germany used to prepare for their upcoming offensives.
On the Continent, raids of Allied commandos on strategic targets, culminating in the disastrous Dieppe Raid, demonstrated the Western Allies' inability to launch an invasion of continental Europe without much better preparation, equipment, and operational security.
In August 1942, the Allies succeeded in repelling a second attack against El Alamein and, at a high cost, managed to deliver desperately needed supplies to the besieged Malta.
A few months later, the Allies commenced an attack of their own in Egypt, dislodging the Axis forces and beginning a drive west across Libya.
This attack was followed up shortly after by Anglo-American landings in French North Africa, which resulted in the region joining the Allies.
Hitler responded to the French colony's defection by ordering the occupation of Vichy France; although Vichy forces did not resist this violation of the armistice, they managed to scuttle their fleet to prevent its capture by German forces.
The firebombing of Hamburg was among the first attacks in this campaign, inflicting significant casualties and considerable losses on infrastructure of this important industrial centre.
Allies gain momentum (1943–44)
After the Guadalcanal Campaign, the Allies initiated several operations against Japan in the Pacific.
In May 1943, Canadian and US forces were sent to eliminate Japanese forces from the Aleutians.
Soon after, the United States, with support from Australia, New Zealand and Pacific Islander forces, began major ground, sea and air operations to isolate Rabaul by capturing surrounding islands, and breach the Japanese Central Pacific perimeter at the Gilbert and Marshall Islands.
In April, the Allies launched an operation to retake Western New Guinea.
In the Soviet Union, both the Germans and the Soviets spent the spring and early summer of 1943 preparing for large offensives in central Russia.
On 4 July 1943, Germany attacked Soviet forces around the Kursk Bulge.
Within a week, German forces had exhausted themselves against the Soviets' deeply echeloned and well-constructed defences, and for the first time in the war Hitler cancelled the operation before it had achieved tactical or operational success.
This decision was partially affected by the Western Allies' invasion of Sicily launched on 9 July, which, combined with previous Italian failures, resulted in the ousting and arrest of Mussolini later that month.
On 12 July 1943, the Soviets launched their own counter-offensives, thereby dispelling any chance of German victory or even stalemate in the east.
The Soviet victory at Kursk marked the end of German superiority, giving the Soviet Union the initiative on the Eastern Front.
Germany with the help of fascists responded by disarming Italian forces that were in many places without superior orders, seizing military control of Italian areas, and creating a series of defensive lines.
The Western Allies fought through several lines until reaching the main German defensive line in mid-November.
German operations in the Atlantic also suffered.
By May 1943, as Allied counter-measures became increasingly effective, the resulting sizeable German submarine losses forced a temporary halt of the German Atlantic naval campaign.
The former conference determined the post-war return of Japanese territory and the military planning for the Burma campaign, while the latter included agreement that the Western Allies would invade Europe in 1944 and that the Soviet Union would declare war on Japan within three months of Germany's defeat.
From November 1943, during the seven-week Battle of Changde, the Chinese forced Japan to fight a costly war of attrition, while awaiting Allied relief.
In January 1944, the Allies launched a series of attacks in Italy against the line at Monte Cassino and tried to outflank it with landings at Anzio.
This delay slowed subsequent Soviet operations in the Baltic Sea region.
The Allied offensives in Italy had succeeded and, at the expense of allowing several German divisions to retreat, on 4 June Rome was captured.
The Allies had mixed success in mainland Asia.
In March 1944, the Japanese launched the first of two invasions, an operation against British positions in Assam, India, and soon besieged Commonwealth positions at Imphal and Kohima.
In May 1944, British forces mounted a counter-offensive that drove Japanese troops back to Burma by July, and Chinese forces that had invaded northern Burma in late 1943 besieged Japanese troops in Myitkyina.
The second Japanese invasion of China aimed to destroy China's main fighting forces, secure railways between Japanese-held territory and capture Allied airfields.
Allies close in (1944)
After reassigning several Allied divisions from Italy, they also attacked southern France.
These landings were successful, and led to the defeat of the German Army units in France.
Paris was liberated on 25 August by the local resistance assisted by the Free French Forces, both led by General Charles de Gaulle, and the Western Allies continued to push back German forces in western Europe during the latter part of the year.
An attempt to advance into northern Germany spearheaded by a major airborne operation in the Netherlands failed.
After that, the Western Allies slowly pushed into Germany, but failed to cross the Rur river in a large offensive.
In Italy, Allied advance also slowed due to the last major German defensive line.
Soon after that, another Soviet strategic offensive forced German troops from Western Ukraine and Eastern Poland.
The Soviets formed the Polish Committee of National Liberation to control territory in Poland and combat the Polish Armia Krajowa; The Soviet Red Army remained in the Praga district on the other side of the Vistula and watched passively as the Germans quelled the Warsaw Uprising initiated by the Armia Krajowa.
The Soviet Red Army's strategic offensive in eastern Romania cut off and destroyed the considerable German troops there and triggered a successful coup d'état in Romania and in Bulgaria, followed by those countries' shift to the Allied side.
By this point, the Communist-led Partisans under Marshal Josip Broz Tito, who had led an increasingly successful guerrilla campaign against the occupation since 1941, controlled much of the territory of Yugoslavia and engaged in delaying efforts against German forces further south.
Unlike impressive Soviet victories in the Balkans, bitter Finnish resistance to the Soviet offensive in the Karelian Isthmus denied the Soviets occupation of Finland and led to a Soviet-Finnish armistice on relatively mild conditions, although Finland was forced to fight their former ally Germany.
Soon after, they invaded the province of Guangxi, winning major engagements against Chinese forces at Guilin and Liuzhou by the end of November and successfully linking up their forces in China and Indochina by mid-December.
In the Pacific, US forces continued to press back the Japanese perimeter.
These defeats led to the resignation of the Japanese Prime Minister, Hideki Tojo, and provided the United States with air bases to launch intensive heavy bomber attacks on the Japanese home islands.
In late October, American forces invaded the Filipino island of Leyte; soon after, Allied naval forces scored another large victory in the Battle of Leyte Gulf, one of the largest naval battles in history.
Axis collapse, Allied victory (1944–45)
On 16 December 1944, Germany made a last attempt on the Western Front by using most of its remaining reserves to launch a massive counter-offensive in the Ardennes and along with the French-German border to split the Western Allies, encircle large portions of Western Allied troops and capture their primary supply port at Antwerp to prompt a political settlement.
By January, the offensive had been repulsed with no strategic objectives fulfilled.
In Italy, the Western Allies remained stalemated at the German defensive line.
On 4 February Soviet, British, and US leaders met for the Yalta Conference.
They agreed on the occupation of post-war Germany, and on when the Soviet Union would join the war against Japan.
In two weeks, the offensive had been repulsed, the Soviets advanced to Vienna, and captured the city.
American and Soviet forces met at the Elbe river on 25 April, leaving several unoccupied pockets in southern Germany and around Berlin.
Soviet and Polish forces stormed and captured Berlin in late April.
In Italy, German forces surrendered on 29 April.
On 30 April, the Reichstag was captured, signalling the military defeat of Nazi Germany, Berlin garrison surrendered on 2 May.
Several changes in leadership occurred during this period.
On 12 April, President Roosevelt died and was succeeded by Harry S. Truman.
German Army Group Centre resisted in Prague until 11 May.
A devastating bombing raid on Tokyo of 9–10 March was the deadliest conventional bombing raid in history.
In May 1945, Australian troops landed in Borneo, over-running the oilfields there.
Chinese forces started a counterattack in the Battle of West Hunan that occurred between 6 April and 7 June 1945.
At the same time, American submarines cut off Japanese imports, drastically reducing Japan's ability to supply its overseas forces.
On 11 July, Allied leaders met in Potsdam, Germany.
They confirmed earlier agreements about Germany, and the American, British and Chinese governments reiterated the demand for unconditional surrender of Japan, specifically stating that "the alternative for Japan is prompt and utter destruction".
The call for unconditional surrender was rejected by the Japanese government, which believed it would be capable of negotiating for more favourable surrender terms.
These two events persuaded previously adamant Imperial Army leaders to accept surrender terms.
The former became a neutral state, non-aligned with any political bloc.
The latter was divided into western and eastern occupation zones controlled by the Western Allies and the Soviet Union.
A denazification programme in Germany led to the prosecution of Nazi war criminals in the Nuremberg trials and the removal of ex-Nazis from power, although this policy moved towards amnesty and re-integration of ex-Nazis into West German society.
Germany lost a quarter of its pre-war (1937) territory.
Among the eastern territories, Silesia, Neumark and most of Pomerania were taken over by Poland, and East Prussia was divided between Poland and the Soviet Union, followed by the expulsion to Germany of the nine million Germans from these provinces, as well as three million Germans from the Sudetenland in Czechoslovakia.
By the 1950s, one-fifth of West Germans were refugees from the east.
The Soviet Union also took over the Polish provinces east of the Curzon line, from which 2 million Poles were expelled; north-east Romania, parts of eastern Finland, and the three Baltic states were incorporated into the Soviet Union.
In an effort to maintain world peace, the Allies formed the United Nations, which officially came into existence on 24 October 1945, and adopted the Universal Declaration of Human Rights in 1948 as a common standard for all member nations.
The five permanent members remain so to the present, although there have been two seat changes, between the Republic of China and the People's Republic of China in 1971, and between the Soviet Union and its successor state, the Russian Federation, following the dissolution of the Soviet Union in 1991.
The alliance between the Western Allies and the Soviet Union had begun to deteriorate even before the war was over.
Germany had been de facto divided, and two independent states, the Federal Republic of Germany (West Germany) and the German Democratic Republic (East Germany), were created within the borders of Allied and Soviet occupation zones.
The rest of Europe was also divided into Western and Soviet spheres of influence.
Most eastern and central European countries fell into the Soviet sphere, which led to establishment of Communist-led regimes, with full or partial support of the Soviet occupation authorities.
Separate republics emerged on both sides of the 38th parallel in 1948, each claiming to be the legitimate government for all of Korea, which led ultimately to the Korean War.
In China, nationalist and communist forces resumed the civil war in June 1946.
Communist forces were victorious and established the People's Republic of China on the mainland, while nationalist forces retreated to Taiwan in 1949.
The global economy suffered heavily from the war, although participating nations were affected differently.
The United States emerged much richer than any other nation, leading to a baby boom, and by 1950 its gross domestic product per person was much higher than that of any of the other powers, and it dominated the world economy.
The UK and US pursued a policy of industrial disarmament in Western Germany in the years 1945–1948.
Because of international trade interdependencies this led to European economic stagnation and delayed European recovery for several years.
Recovery began with the mid-1948 currency reform in Western Germany, and was sped up by the liberalisation of European economic policy that the Marshall Plan (1948–1951) both directly and indirectly caused.
The post-1948 West German recovery has been called the German economic miracle.
By contrast, the United Kingdom was in a state of economic ruin, and although receiving a quarter of the total Marshall Plan assistance, more than any other European country, it continued in relative economic decline for decades.
The Soviet Union, despite enormous human and material losses, also experienced rapid increase in production in the immediate post-war era.
Japan recovered much later.
China returned to its pre-war industrial production by 1952.
Main article: Historiography of World War II
Casualties and war crimes
Estimates for the total number of casualties in the war vary, because many deaths went unrecorded.
Most suggest that some 60 million people died in the war, including about 20 million military personnel and 40 million civilians.
The Soviet Union alone lost around 27 million people during the war, including 8.7 million military and 19 million civilian deaths.
A quarter of the people in the Soviet Union were wounded or killed.
Germany sustained 5.3 million military losses, mostly on the Eastern Front and during the final battles in Germany.
An estimated 11 to 17 million civilians died as a direct or as an indirect result of Nazi racist policies, including mass killing of around 6 million Jews, along with Roma, homosexuals, at least 1.9 million ethnic Poles and millions of other Slavs (including Russians, Ukrainians and Belarusians), and other ethnic and minority groups.
At the same time about 10,000–15,000 Ukrainians were killed by the Polish Home Army and other Polish units, in reprisal attacks.
In Asia and the Pacific, between 3 million and more than 10 million civilians, mostly Chinese (estimated at 7.5 million), were killed by the Japanese occupation forces.
The most infamous Japanese atrocity was the Nanking Massacre, in which fifty to three hundred thousand Chinese civilians were raped and murdered.
Mitsuyoshi Himeta reported that 2.7 million casualties occurred during the Sankō Sakusen.
The Soviet Union was responsible for the Katyn massacre of 22,000 Polish officers, and the imprisonment or execution of thousands of political prisoners by the NKVD, along with mass civilian deportations to Siberia, in the Baltic states and eastern Poland annexed by the Red Army.
The mass bombing of cities in Europe and Asia has often been called a war crime, although no positive or specific customary international humanitarian law with respect to aerial warfare existed before or during World War II.
The USAAF firebombed a total of 67 Japanese cities, killing 393,000 civilians and destroying 65% of built-up areas.
Genocide, concentration camps, and slave labour
Main articles: Genocide, The Holocaust, Nazi concentration camps, Extermination camp, Forced labour under German rule during World War II, Kidnapping of children by Nazi Germany, and Nazi human experimentation
Nazi Germany was responsible for the Holocaust (which killed approximately 6 million Jews) as well as for killing 2.7 million ethnic Poles and 4 million others who were deemed "unworthy of life" (including the disabled and mentally ill, Soviet prisoners of war, Romani, homosexuals, Freemasons, and Jehovah's Witnesses) as part of a programme of deliberate extermination, in effect becoming a "genocidal state".
Soviet POWs were kept in especially unbearable conditions, and 3.6 million Soviet POWs out of 5.7 died in Nazi camps during the war.
The Soviet Gulag became a de facto system of deadly camps during 1942–43, when wartime privation and hunger caused numerous deaths of inmates, including foreign citizens of Poland and other countries occupied in 1939–40 by the Soviet Union, as well as Axis POWs.
By the end of the war, most Soviet POWs liberated from Nazi camps and many repatriated civilians were detained in special filtration camps where they were subjected to NKVD evaluation, and 226,127 were sent to the Gulag as real or perceived Nazi collaborators.
Japanese prisoner-of-war camps, many of which were used as labour camps, also had high death rates.
The International Military Tribunal for the Far East found the death rate of Western prisoners was 27 per cent (for American POWs, 37 per cent), seven times that of POWs under the Germans and Italians.
While 37,583 prisoners from the UK, 28,500 from the Netherlands, and 14,473 from the United States were released after the surrender of Japan, the number of Chinese released was only 56.
At least five million Chinese civilians from northern China and Manchukuo were enslaved between 1935 and 1941 by the East Asia Development Board, or Kōain, for work in mines and war industries.
After 1942, the number reached 10 million.
About 270,000 of these Javanese labourers were sent to other Japanese-held areas in South East Asia, and only 52,000 were repatriated to Java.
In Europe, occupation came under two forms.
In Western, Northern, and Central Europe (France, Norway, Denmark, the Low Countries, and the annexed portions of Czechoslovakia) Germany established economic policies through which it collected roughly 69.5 billion reichsmarks (27.8 billion US dollars) by the end of the war; this figure does not include the sizeable plunder of industrial products, military equipment, raw materials and other goods.
Thus, the income from occupied nations was over 40 per cent of the income Germany collected from taxation, a figure which increased to nearly 40 per cent of total German income as the war went on.
Unlike in the West, the Nazi racial policy encouraged extreme brutality against what it considered to be the "inferior people" of Slavic descent; most German advances were thus followed by mass executions.
Although resistance groups formed in most occupied territories, they did not significantly hamper German operations in either the East or the West until late 1943.
In Asia, Japan termed nations under its occupation as being part of the Greater East Asia Co-Prosperity Sphere, essentially a Japanese hegemony which it claimed was for purposes of liberating colonised peoples.
Although Japanese forces were sometimes welcomed as liberators from European domination, Japanese war crimes frequently turned local public opinion against them.
During Japan's initial conquest it captured 4,000,000 barrels (640,000 m) of oil (~5.5×10 tonnes) left behind by retreating Allied forces, and by 1943 was able to get production in the Dutch East Indies up to 50 million barrels (~6.8×10^ t), 76 per cent of its 1940 output rate.
Home fronts and production
In Europe, before the outbreak of the war, the Allies had significant advantages in both population and economics.
In 1938, the Western Allies (United Kingdom, France, Poland and the British Dominions) had a 30 per cent larger population and a 30 per cent higher gross domestic product than the European Axis powers (Germany and Italy); if colonies are included, the Allies had more than a 5:1 advantage in population and a nearly 2:1 advantage in GDP.
In Asia at the same time, China had roughly six times the population of Japan but only an 89 per cent higher GDP; this is reduced to three times the population and only a 38 per cent higher GDP if Japanese colonies are included.
The United States produced about two-thirds of all the munitions used by the Allies in WWII, including warships, transports, warplanes, artillery, tanks, trucks, and ammunition.
Though the Allies' economic and population advantages were largely mitigated during the initial rapid blitzkrieg attacks of Germany and Japan, they became the decisive factor by 1942, after the United States and Soviet Union joined the Allies, as the war largely settled into one of attrition.
While the Allies' ability to out-produce the Axis is often attributed to the Allies having more access to natural resources, other factors, such as Germany and Japan's reluctance to employ women in the labour force, Allied strategic bombing, and Germany's late shift to a war economy contributed significantly.
Additionally, neither Germany nor Japan planned to fight a protracted war, and had not equipped themselves to do so.
To improve their production, Germany and Japan used millions of slave labourers; Germany used about 12 million people, mostly from Eastern Europe, while Japan used more than 18 million people in Far East Asia.
Advances in technology and warfare
Main article: Technology during World War II
Innovation included airlift (the capability to quickly move limited high-priority supplies, equipment, and personnel); and of strategic bombing (the bombing of enemy industrial and population centres to destroy the enemy's ability to wage war).
The use of the jet aircraft was pioneered and, though late introduction meant it had little impact, it led to jets becoming standard in air forces worldwide.
Although aeronautical warfare had relatively little success at the start of the war, actions at Taranto, Pearl Harbor, and the Coral Sea established the carrier as the dominant capital ship in place of the battleship.
Carriers were also more economical than battleships because of the relatively low cost of aircraft and their not requiring to be as heavily armoured.
Submarines, which had proved to be an effective weapon during the First World War, were anticipated by all sides to be important in the second.
The British focused development on anti-submarine weaponry and tactics, such as sonar and convoys, while Germany focused on improving its offensive capability, with designs such as the Type VII submarine and wolfpack tactics.
Land warfare changed from the static front lines of trench warfare of World War I, which had relied on improved artillery that outmatched the speed of both infantry and cavalry, to increased mobility and combined arms.
The tank, which had been used predominantly for infantry support in the First World War, had evolved into the primary weapon.
In the late 1930s, tank design was considerably more advanced than it had been during World War I, and advances continued throughout the war with increases in speed, armour and firepower.
At the start of the war, most commanders thought enemy tanks should be met by tanks with superior specifications.
This idea was challenged by the poor performance of the relatively light early tank guns against armour, and German doctrine of avoiding tank-versus-tank combat.
This, along with Germany's use of combined arms, were among the key elements of their highly successful blitzkrieg tactics across Poland and France.
Even with large-scale mechanisation, infantry remained the backbone of all forces, and throughout the war, most infantry were equipped similarly to World War I.
The assault rifle, a late war development incorporating many features of the rifle and submachine gun, became the standard postwar infantry weapon for most armed forces.
Most major belligerents attempted to solve the problems of complexity and security involved in using large codebooks for cryptography by designing ciphering machines, the most well known being the German Enigma machine.
Notable examples were the Allied decryption of Japanese naval codes and British Ultra, a pioneering method for decoding Enigma benefiting from information given to the United Kingdom by the Polish Cipher Bureau, which had been decoding early versions of Enigma before the war.
Other technological and engineering feats achieved during, or as a result of, the war include the world's first programmable computers (Z3, Colossus, and ENIAC), guided missiles and modern rockets, the Manhattan Project's development of nuclear weapons, operations research and the development of artificial harbours and oil pipelines under the English Channel.
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/World War II.