Pearl Harbor, land-locked harbor, on the southern coast of Oahu island, Hawaii, W of Honolulu; one of the largest and best natural harbors in the E Pacific Ocean. In the vicinity are many U.S. military installations, including the chief U.S. Pacific naval base, Hickam Air Force Base, Pearl Harbor Naval Air Station, and Camp H. M. Smith, headquarters of the U.S. Pacific Command.
The United States first gained rights there in 1887, when the Hawaiian monarchy permitted a coaling and repair station. After the United States annexed Hawaii in 1900, Pearl Harbor was made a naval base. Harbor improvements and fortifications were later added, especially after the signing of the Berlin Pact in 1940 by the Axis nations.
On Dec. 7, 1941, while negotiations were going on with Japanese representatives in Washington, Japanese carrier-based planes swept in without warning over Oahu and attacked (7:55 descr='[AM]' local time) the bulk of the U.S. Pacific fleet, moored in Pearl Harbor. Nineteen naval vessels, including eight battleships, were sunk or severely damaged; 188 U.S. aircraft were destroyed. Military casualties were 2,280 killed and 1,109 wounded; 68 civilians also died. On Dec. 8, the United States declared war on Japan.
There were many charges of negligence against those responsible for Pearl Harbor's defense. A special commission appointed by President Franklin D. Roosevelt accused the army and navy commanders at Hawaii of dereliction of duty in a report on Jan. 24, 1942. Later army and navy investigations concluded that no valid grounds existed for court-martial. A congressional committee, formed in Sept., 1945, absolved the army and navy commanders in a formal report on July 16, 1946, but censured the War Dept. and the Dept. of the Navy.
Pearl Harbor is now a national historic landmark; a memorial has been built over the sunken hulk of the USS Arizona. The battleship Missouri, site of Japan's surrender, is also preserved there as a memorial.