Pearl Harbor The Japanese bombed Pearl Harbor, Oahu, Hawaii on December 7, 1941 at 7:50 AM on a Sunday morning. There were over 3500 Navy, Army, and Marine troops killed. Four battle ships were sunk and many over military vessels were heavily damaged. The U.S. and Japan had not yet declared war and the U.S. military divisions were not on any type of wartime alert. In fact the Japanese diplomats were in Wash D.C. Conferring on possible ways to resolve their differences. Prior to the bombing the U.S. had broken Japan’s secret code and interpreted Japan’s messages about the bombing of Pearl Ha