World War II

World War II started in September 1939 when German troops invaded Poland. It evolved into an international conflict involving sixty-one countries. Over 100 million people were mobilized for military service in four geographic regions across the globe: Europe, Asia, Africa, and the South Pacific. The war left 55 million people dead (30 million civilians and 25 million soldiers), cost over one trillion dollars, and resulted in more material destruction than any other armed conflict in history.

British Crusader tanks moving to forward positions during the North African Campaign.

Although the war was fought across the world in many countries, a few powers led efforts on both sides. Those who joined, or were forced to join, Germany became known as the Axis Powers. They were led by German dictator Adolf Hitler (1889–1945), Italian dictator Benito Mussolini (1883–1945), and Japanese prime minister Hideki Tojo (1884–1948). The Axis Powers also included Hungary, Bulgaria, Romania, and others.

A contemporary video showing bombing of Hamburg by the Allies.

The opposing countries became known as the Allied Powers, or Allies. They were led primarily by U.S. president Franklin D. Roosevelt (1882–1945; served 1933–45), British prime minister Winston Churchill (1874–1965), and Soviet premier Joseph Stalin (1873–1953).

Soviet Il-2 planes attacking a Wehrmacht column during the Battle of Kursk, 1 July 1943.

Among many others, Canada, Australia, France, and China joined the efforts of the Allies.

British troops firing a mortar during the Battle of Imphal, North East India, 1944.

In the years following World War I (1914–18), the United States had become increasingly isolated from the activities of European nations and other countries. Despite Americans’ desire to remain uninvolved in world currents, the United States was drawn into World War II in 1941.

Allied Invasion of Normandy, 6 June 1944

The war posed great challenges for the nation even as it brought economic benefits and increased international power.

Red Army personnel and equipment crossing a river during the northern Summer of 1944