What happened at Pearl Harbor?

On the morning of Sunday, December 7, 1941, Japanese aircraft launched from carriers struck the US naval base at Pearl Harbor on Oahu in two waves, without a declaration of war. The attack killed about 2,400 Americans and wounded around 1,100, sank or damaged numerous ships including the battleship USS Arizona, which lost over 1,100 crew and remains a memorial on the harbor floor, and destroyed a large portion of the aircraft on the island, many caught on the ground. President Roosevelt addressed Congress the following day, describing the date as one that would live in infamy, and the United States declared war on Japan. Germany and Italy declared war on the United States days later, bringing the country fully into the global conflict.

Japan's strategic reasoning was that crippling the Pacific Fleet would buy time to secure resource-rich territories in Southeast Asia before American power could be brought to bear, at a moment when US embargoes on oil and steel were constraining Japanese operations in China. The calculation failed in an important respect: the American aircraft carriers were at sea and survived, the base's fuel storage and repair facilities were largely untouched, and most of the damaged battleships were eventually raised and returned to service. Carriers rather than battleships proved decisive in the Pacific war that followed.

Two aftermaths belong in any account. The attack ended American isolationism decisively, transforming a divided public debate into near-unanimous support for entering the war. And it triggered Executive Order 9066 in February 1942, under which roughly 120,000 people of Japanese ancestry, the majority of them American citizens, were forcibly removed from the West Coast and held in incarceration camps for the duration of the war, without charges or trials. Congress formally apologized and authorized reparations in the Civil Liberties Act of 1988, describing the policy as motivated by race prejudice, war hysteria, and a failure of political leadership.