The war in the Pacific began in September 1931, as Japan, in a bid for overseas
expansion, occupied Manchuria. In July 1937, Japan invaded China, massacring
nearly 400,000 civilians at Nanking. By 1941, Japan had continued its
overseas conquests with an invasion of French Indo-China, and an attack on
British possessions in Indian, Burma, and the Pacific theatre. Japan’s
aggression led to sanctions by the United States against the nation on oil
and steel. In response, Japan decided to strike against the United States
carrier fleet at Pearl Harbor, Hawaii.