America and World War II

World War II (1941–1945) was the most transformative event in twentieth-century American history. It ended the Great Depression, established the United States as the world's preeminent military and economic superpower, accelerated demands for racial equality, and reshaped the role of women in American society. The war also raised profound moral questions about the use of atomic weapons and the internment of Japanese Americans that continue to resonate.

Key Definition: The Arsenal of Democracy was President Roosevelt's phrase (December 1940) describing America's role as the chief supplier of military equipment to the Allied nations fighting the Axis powers, prior to formal US entry into the war.

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From Isolationism to Intervention

American foreign policy in the 1930s was dominated by isolationism — the conviction, reinforced by disillusionment with World War I, that the United States should avoid entanglement in European conflicts.