December 7, 1941. A swarm of Japanese warplanes descended onto the U.S. naval base of Pearl Harbor delivering a critical blow to the U.S. Pacific fleet. The attack was part of a huge offence by the Japanese military against both the U.S and British, which took place over 7 hours. The Japanese attacked the U.S. held Philippines, Guam, and the British Empire in Malaya, Singapore and Hong Kong. Most of the Pacific fleet were destroyed in the attack at Pearl Harbor. Fifteen ships were sunk, including five battleships and three destroyers. More than 200 aircraft were lost in the attack which killed 2,400 American servicemen.The surprise attack drew the United States irrevocably into World War II. Pictured below are Seamen at Kaneohe Naval Air Station decorating the graves of their fellow sailors killed at Pearl Harbor. Photo: Library of Congress Prints and Photographs.