USS SHAW exploding during the Japanese raid on Pearl Harbor.” December 7, 1941. 80-G-16871. National Archives Identifier: 520590.

World War II was a global war that lasted six years. The vast majority of the world’s countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries.