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World War II

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World War II was the largest and most violent military conflict in human history. Official casualty sources estimate battle deaths at nearly 15 million military personnel and civilian deaths at over 38 million. Fought largely between two opposing military alliances, the Allies and the Axis, the war engulfed Europe, North Africa, much of Asia and the world's oceans. Germany, Japan, and Italy led the loosely cooperating Axis nations. The major Allies were the United States, Great Britain, and the Soviet Union, although a great many other nations committed forces.

The worldwide struggle officially began with the German attack on Poland on September 1, 1939, followed quickly by Great Britain, its Commonwealth dominions, and France declaring war on Germany. With the defeat of France in 1940, Great Britain fought off a German air campaign and escaped invasion. The German invasion of the Soviet Union in June 1941 brought that nation into the war and opened a major new theater. In Asia, the Japanese had been fighting to take over China since 1931. A surprise Japanese attack on the American fleet at Pearl Harbor in Hawaii in December 1941 brought the United States into the war on the side of the Allies and opened a 45-month struggle in the Pacific and Indian Oceans and Asia. The American and British-led invasions of North Africa and then Italy, along with Soviet successes, turned the tide against the Axis in Europe. The Allied landings in Normandy in June 1944 opened a western front and, coupled with continued Soviet offensives in the east, brought about the eventual defeat and unconditional surrender of Germany in May 1945. The war culminated with the United States dropping atomic bombs on two Japanese cities and the unconditional surrender of Japan on 2 September 1945.