World War II, the largest and deadliest conflict in human history, involved more than 50 nations and was fought on land, sea and air in nearly every part of the world.
Also known as the Second World War, it was caused in part by the economic crisis of the Great Depression and by political tensions left unresolved following the end of World War I. The war began when Nazi Germany invaded Poland in and raged across the globe until , when Japan surrendered to the United States after atomic bombs were dropped on Hiroshima and Nagasaki. By the end of World War II, an estimated 60 to 80 million people had died, including up to 55 million civilians, and numerous cities in Europe and Asia were reduced to rubble.
The legacy of the war included the creation of the United Nations as a peacekeeping force and geopolitical rivalries that resulted in the Cold War. The devastation of the Great War as World War I was known at the time had greatly destabilized Europe, and in many respects World War II grew out of issues left unresolved by that earlier conflict.
Did you know? As early as , in his memoir and propaganda tract "Mein Kampf" My Struggle , Adolf Hitler had predicted a general European war that would result in "the extermination of the Jewish race in Germany.
In the mids, he secretly began the rearmament of Germany, a violation of the Versailles Treaty. After signing alliances with Italy and Japan against the Soviet Union , Hitler sent troops to occupy Austria in and the following year annexed Czechoslovakia. Hitler had long planned an invasion of Poland, a nation to which Great Britain and France had guaranteed military support if it were attacked by Germany. The pact with Stalin meant that Hitler would not face a war on two fronts once he invaded Poland, and would have Soviet assistance in conquering and dividing the nation itself.
