World War II was a global conflict that lasted from 1939 to 1945. It involved the majority of the world's nations, including all of the great powers, organized into two opposing military alliances: the Allies and the Axis. The war was fought between two main groups, the Allies, who were led by the United States, Great Britain, and the Soviet Union, and the Axis powers, which included Germany, Japan, and Italy. As a superpower, the United States played a critical… Read more.