World War II

World War II or the Second World War (1 September 1939 – 2 September 1945) was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II was the deadliest conflict in history, resulting in 70 to 85 million deaths, more than half of which were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes. The causes of World War II included unresolved tensions in the aftermath of World War I and the rises of fascism in Europe and militarism in Japan. Key events preceding the war included Japan's invasion of Manchuria in 1931, the Spanish Civil War, the outbreak of the Second Sino-Japanese War in 1937, and Germany's annexations of Austria and the Sudetenland. World War II is generally considered to have begun on 1 September 1939, when Nazi Germany, under Adolf Hitler, invaded Poland, after which the United Kingdom and France declared war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact. In 1940, the Soviets annexed the Baltic states and parts of Finland and Romania. After the fall of France in June 1940, the war continued mainly between Germany and the British Empire, with fighting in the Balkans, Mediterranean, and Middle East, the aerial Battle of Britain and the Blitz, and naval Battle of the Atlantic. Through campaigns and treaties, Germany gained control of much of continental Europe and formed the Axis alliance with Italy, Japan, and other countries. In June 1941, Germany led an invasion of the Soviet Union, opening the Eastern Front and initially making large territorial gains. In December 1941, Japan attacked American and British territories in Asia and the Pacific, including at Pearl Harbor in Hawaii, leading the United States to enter the war against Japan and Germany. Japan conquered much of coastal China and Southeast Asia, but its advances in the Pacific were halted in June 1942 at the Battle of Midway. In late 1942, Axis forces were defeated in North Africa and at Stalingrad in the Soviet Union, and in 1943 their continued defeats on the Eastern Front, an Allied invasion of Italy, and Allied offensives in the Pacific forced them into retreat on all fronts. In 1944, the Western Allies invaded France at Normandy as the Soviet Union recaptured its pre-war territory and the U.S. crippled Japan's navy and captured key Pacific islands. The war in Europe concluded with the liberation of German-occupied territories; invasions of Germany by the Western Allies and the Soviet Union, which culminated in the fall of Berlin to Soviet troops; and Germany's unconditional surrender on 8 May 1945. On 6 and 9 August, the U.S. dropped atomic bombs on Hiroshima and Nagasaki in Japan. Faced with an imminent Allied invasion, the prospect of further atomic bombings, and a Soviet declaration of war and invasion of Manchuria, Japan announced its unconditional surrender on 15 August, and signed a surrender document on 2 September 1945. World War II transformed the political, economic, and social structures of the world, and established the foundation of international relations for the rest of the 20th century and into the 21st century. The United Nations was created to foster international cooperation and prevent future conflicts, with the victorious great powers—China, France, the Soviet Union, the UK, and the U.S.—becoming the permanent members of its security council. The Soviet Union and U.S. emerged as rival global superpowers, setting the stage for the half-century Cold War. In the wake of Europe's devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia. Many countries whose industries had been damaged moved towards economic recovery and expansion.

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