World War II (WWII) officially began in Europe in 1939. However, the United States maintained an isolationist stance and refused to become involved beyond manufacturing planes, ships, and weapons to be sent to Allied forces. Meanwhile, the war spread to Asia, where Imperial Japan took advantage of the chaos in Europe to invade parts of China, including territories that had long been under British and French control, such as French Indochina. Though the US still refused to join the war effort, President Roosevelt moved the bulk of the Pacific Fleet to Hawaii, the closest territory to Japan, as a show of force.

In response, the Imperial Japanese Navy attacked the Naval base at Pearl Harbor in Hawaii on December 7, 1941, hoping to impair American forces and forestall their entry into the war. The surprise attack came on a Sunday morning, when many American sailors, on their day off were slow to respond. The attack lasted only two hours but resulted in the damage or destruction of 20 American battleships and 350 planes, as well as the deaths of approximately 2,400 American sailors, Marines, and soldiers. More than half of these casualties came from the explosion of the USS Arizona, which remains in Pearl Harbor to this day, as a memorial.