A history of the attack on Pearl Harbor

The attack on Pearl Harbor was a surprise military strike by Japanese bombers on United States military and naval forces in Hawaii on Dec. 7, 1941. According to the National Archives, the event devastated the U.S. Pacific Fleet and catapulted the United States into World War II.

The morning of the attack

On the morning of Dec. 7, 1941, Japanese forces attacked the U.S. naval base on the island of Oahu, Hawaii. In less than two hours, the attack killed or wounded more than 3,500 Americans. Although diplomatic relations between the United States and Japan were deteriorating at the time, they had not been broken off.

At the Opana Radar Station, Privates George E. Elliot, Jr. and Joseph L. Lockard tracked a large number of approaching aircraft on radar. A control officer mistakenly believed the radar signals indicated the arrival of scheduled American B-17 bombers. In reality, the radar tracked the first wave of Japanese bombers and torpedo planes that struck Pearl Harbor.

One hour after the bombing began in Oahu, the Japanese Ambassador delivered a formal reply to an American message to the Secretary of State. The reply stated that it seemed useless to continue diplomatic negotiations, but it contained no threat of war or armed attack.

The presidential response

Early in the afternoon of Dec. 7, President Franklin D. Roosevelt and Harry Hopkins, his primary foreign policy advisor, received a telephone call from Secretary of War Henry Stimson informing them of the attack. At about 5 p.m., after meeting with military advisers, Roosevelt dictated a request for a declaration of war to his secretary, Grace Tully. Roosevelt had composed the speech in his head, choosing a short appeal to the public over the detailed list of Japanese betrayals that Secretary of State Cordell Hull had recommended.

Roosevelt then revised the typed draft, updating military information and selecting alternative wordings to strengthen the tone. He changed the critical first line from “a date which will live in world history” to “a date which will live in infamy,” according to the National Archives. Grace Tully prepared the final reading copy, which Roosevelt altered in three additional places.

The declaration of war

On Dec. 8 at 12:30 p.m., Roosevelt delivered his address to a joint session of Congress and the nation via radio. In his speech, he noted that Japanese forces had also attacked Malaya, Hong Kong, Guam, the Philippine Islands, Wake Island, and Midway Island. The Senate responded with a unanimous vote to support the war, while the House had a single dissenting vote from pacifist Representative Jeanette Rankin of Montana.

Roosevelt signed the declaration of war at 4 p.m. that same afternoon. The American people were outraged by the attack and instantly united in a massive mobilization for war. The incident also strengthened American resolve to guard against future lapses in military alertness.

The postwar investigation

Lawmakers formed the Joint Committee on the Investigation of the Pearl Harbor Attack four years after the strike. The committee was tasked with investigating the facts and circumstances leading up to and following the attack. It sought to determine if shortcomings or failures on the U.S. side contributed to the disaster.

The committee was also formed to suggest changes that might protect the country from future attacks. Public hearings for the investigation began on Nov. 15, 1945. The hearings continued until May 31, 1946.