The attack on Pearl Harbor by the Japanese Imperial General Headquarters was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941. The attack was intended as a preventive action in order to keep the U. S. Pacific Fleet from interfering with military actions the Empire of Japan was planning in Southeast Asia against overseas territories of the United Kingdom, the Netherlands, and the United States. The base was attacked by Japanese fighters, bombers and torpedo planes in two waves, launched from six aircraft carriers.
All eight U. S. Navy battleships were damaged, with four being sunk. Of the eight damaged six were raised, repaired and returned to service later in the war. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one minelayer. 188 U. S. aircraft were destroyed; 2,402 Americans were killed and 1,282 wounded. The power station, shipyard, maintenance, and fuel and torpedo storage facilities, as well as the submarine piers and headquarters building were not attacked.
The attack came as a profound shock to the American people and led directly to the American entry into World War II in both the Pacific and European theaters. The following day, the United States declared war on Japan. There were numerous historical examples for unannounced military action by Japan. However, the lack of any formal warning, particularly while negotiations were still apparently ongoing, led President Franklin D. Roosevelt to proclaim December 7, 1941, “a date which will live in infamy”.