World War II or the Second World War, often abbreviated as WWII or WW2, was a worldwide military conflict; the amalgamation of two separate conflicts, one beginning in Asia, 1937, as the Second Sino-Japanese War and the other beginning in Europe, 1939, with the invasion of Poland. It is regarded as the historical successor to World War I.



This global conflict split a majority of the world's nations into two opposing military alliances: the Allies and the Axis. Spanning much of the globe, World War II resulted in the deaths of over 70 million people, making it the deadliest conflict in human history.



World War II was the most widespread war in history, and countries involved mobilized more than 100 million military personnel. Total war erased the distinction between civil and military resources and saw 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. For example, nearly 11 million of the civilian casualties were victims of the Holocaust, which was largely conducted in Eastern Europe, and the Soviet Union.



The conflict ended in an Allied victory. As a result, the United States and Soviet Union emerged as the world's two leading superpowers, setting the stage for the Cold War for the next 45 years. Self determination gave rise to decolonization/independence movements in Asia and Africa, while Europe itself began traveling the road leading to integration.