On 7 December 1941, Japanese forces executed a surprise attack on Pearl Harbor, a U.S. naval base near Honolulu, Hawaii.
The attack by the approximately 350 Japanese aircrafts damaged eighteen U.S. naval vessels, including eight battleships; destroyed 300 US aircraft; and killed 2,403 men, including 68 civilians. By comparison, Japan suffered relatively light casualties and lost only 29 aircraft and a handful of mini-submarines.
Japan initiated the attack to prevent the United States Pacific Fleet from interfering with its planned military actions in Southeast Asia. By attacking the Pearl Harbor base, Japan would have full control over the Pacific; the base was relatively vulnerable despite being a significant strategic asset for the U.S.
Japan believed that the United Kingdom, France and the Netherlands would be unable to defend their Asian colonial holdings due to their participation in World War II. In fact, eight hours after the attack, Japan attacked Singapore, Hong Kong, and Malaya, all of which were under the rule of the United Kingdom.
While the attack initially seemed like a strategic success for the Japanese, it fell short of its initial goals for several reasons: most of the American fleet and aircraft carriers remained intact and three carriers were out at sea; U.S. oil supplies, submarine fleet, and repair facilities remained undamaged; and perhaps most importantly, it led to America’s involvement in World War II.
The day following the attack, United States President Franklin D. Roosevelt asked Congress to declare war on Japan during a joint session of the U.S. Congress: “Yesterday, December 7, 1941—a date which will live in infamy—the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan.” He went on to say, “No matter how long it may take us to overcome this premeditated invasion, the American people in their righteous might will win through to absolute victory. I believe I interpret the will of the Congress and of the people when I assert that we will not only defend ourselves to the uttermost but will make very certain that this form of treachery shall never endanger us again.”
Following Roosevelt’s speech, the Senate voted to declare war on Japan by a vote of 82 to 0, and the House of Representatives approved the resolution by 388 to 1.
The attack on Pearl Harbor had significant geopolitical effects beyond Japan and the United States. In what is seen by many historians as one of his greatest errors of World War II, Adolf Hitler applauded the attack and along with Italy declared war on the United States even though America had only declared war against Japan. Three days after the Pearl Harbor attack, Germany and Italy formally declared war against the United States, leading the American government to declare war on Germany and Italy
Less than a year after the Pearl Harbor attack, American soldiers would be fighting German forces and America would be continuing its material support of the Soviet Union, Nazi Germany’s primary enemy in the early stages of World War II. By the end of the war, 400,000 American soldiers' lives would be lost.
Reflecting on the attack’s effect on America’s foreign policy, Professor Peter Harris of Colorado State University, wrote, “It [sidelined] isolationism as a powerful force in domestic politics and [made] overseas engagement the accepted norm.”