World War II (abbreviated
WWII or
WW2), or the
Second World War, was a
worldwide militaryconflict which lasted from
1939 to
1945. World War II was the
amalgamation of two conflicts, one starting in
Asia as the
Second Sino-Japanese War and the other beginning in
Europe with the
Invasion of Poland.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 mobilization 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.