World War 2

World War II, or the Second World War, was a worldwide military conflict, the combination of what had initially been two separate conflicts. The first began in Asia in 1937 as the Second Sino-Japanese War; the other began in Europe in 1939 with the German invasion of Poland. This global conflict split the majority of the world's nations into two opposing military alliances: the Allies and the Axis Powers. Spanning much of the globe, World War II resulted in the death of over 70 million people, making it the deadliest conflict in human history.
World War II involved the mobilization of over 100 million military personnel, making it the most widespread war in history. The war placed the participants in a state of "total war", erasing the distinction between civil and military resources. This resulted in the complete activation of a nation's economic, industrial, and scientific capabilities for the purposes of the war effort; nearly two-thirds of those killed in the war were civilians. Nearly 11 million of these civilian casualties were victims of the Holocaust—which was conducted by Nazi Germany—largely in Eastern Europe and the Soviet Union.The financial cost of the war is estimated at about a trillion 1944 U.S. dollars worldwide,making it the most expensive war in capital as well as lives.
The Allies were victorious, and, as a result, the United States and Soviet Union emerged as the world's two leading superpowers. This set the stage for the Cold War, which lasted for the next 45 years. The United Nations was formed in hopes of preventing another such conflict. The self determination spawned by the war gave rise to decolonization movements in Asia and Africa, while Europe itself began moving toward integration.