Overview
World War II was a global war that started in 1939 and ended in 1945. It involved most of the world's nations eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, with more than 100 million people serving in military units. In a state of total war, the nations placed their entire economic, industrial, and scientific capabilities in the war erasing the line between civilian and military resources. Marked by significant events involving the Holocaust and the only use of nuclear weapons in warfare, it resulted in 50 million to over 73 million casualties These deaths make World War II by far the deadliest conflict in all of human history.