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Attack on Pearl Harbor
December 7, 1941· Battle· Americas & Oceania
Well documentedSolid records, physical evidence or scientific consensus.
Japan's surprise air attack on the US Pacific Fleet at Pearl Harbor, Hawaii, on December 7, 1941, which brought America into World War II.
See it on the History map →What happened
After the US cut off oil exports to Japan in 1941 over its war in China and its move into Indochina, Japan planned to seize Southeast Asia's resources and knock out the US fleet first. Six aircraft carriers launched about 350 planes in two waves. They sank or damaged 19 ships, including eight battleships, and destroyed nearly 190 aircraft. About 2,400 Americans were killed. The US carriers were at sea and escaped. Within hours Japan also struck the Philippines, Malaya and Hong Kong.
Why it matters
It ended American isolationism overnight. The US declared war the next day, and Germany declared war on the US four days later, making the war truly global.
How we know
US Navy records, several official investigations, Japanese planning documents and pilots' accounts, and the sunken USS Arizona, now a memorial.
Still debated
Theories that Roosevelt knew in advance persist, but historians have found no credible evidence; the real debate is over missed warnings and intelligence failures.
Connections (2)
▸Attack on Pearl Harbor brought the United States into World War IIWell documented
The connection
The US had been aiding Britain and China but stayed out of the fighting. The attack united American opinion: Congress declared war on Japan on December 8, 1941, with one dissenting vote. Germany and Italy declared war on the US on December 11, joining the European and Pacific wars into one global conflict.
When and how
Washington, December 8–11, 1941; Roosevelt called December 7 'a date which will live in infamy'.
How we know
Congressional records, Roosevelt's speech, and Germany's formal declaration of war on December 11, 1941.
Debates and open questions
Why Hitler declared war on the US, which his treaty with Japan did not require, is still debated.
▸Attack on Pearl Harbor began the US–Japan war that ended after Atomic bombings of Hiroshima and NagasakiWell documented
The connection
Pearl Harbor began nearly four years of Pacific war: Midway in 1942, island-hopping campaigns, and firebombing of Japanese cities. Iwo Jima and Okinawa in 1945 were very costly, and planners feared huge losses invading Japan. President Truman approved using the new atomic bombs, aiming to force surrender without an invasion.
When and how
The Pacific, December 1941 to August 1945; Truman approved the bombings after the first atomic test in New Mexico on July 16, 1945.
How we know
Truman's August 6 statement linked them directly: 'The Japanese began the war from the air at Pearl Harbor. They have been repaid many fold.'
Debates and open questions
How large the projected invasion casualties really were, and whether postwar accounts inflated them to justify the bombings, is debated.