10.6World War II

The United States mobilized on a staggering scale, its factories becoming the "arsenal of democracy" and its armed forces swelling to millions. Americans fought across two vast theaters, in Europe against Germany and Italy and across the Pacific against Japan, in alliance with Britain and the Soviet Union.

The war reshaped society at home: women entered factories in huge numbers, Black Americans pressed for a "Double V"—victory abroad and against discrimination at home—and Japanese Americans were unjustly interned. Allied victory came in 1945, in Europe in May and over Japan in August after atomic bombs devastated Hiroshima and Nagasaki. The war ended the Depression and left the United States the world's dominant power.