On the morning of December 7, 1941, a Japanese squadron attacked the U.S naval base of Pearl Harbor in Hawaii. This caused the United States entering World War II. The attack was intended to keep the United States' attention away from the Germans in the European Theater, after talks with the U.S. broke down, and an embargo on supplies from the U.S. began, the Japanese had to attack the U.S. Because the country is a very small island and can't produce its own resources, it had relied on the U.S. to be suplied with oil and other products. The base was attacked by 353 Japanese aircraft in 2 waves launched from six aircraft carriers. Many of the American Sailors were ashore, and never expected an attack from anywhere, so when the Japanese attacked, the Americans were caught in a vulnerable position. The Japanese were expecting the carriers to be ashore during the attack, and this would've kept the Americans out of war, but luckily, they were out of port and they escaped from being sunked.

Four United States Navy battleships were sunk and all of the four other battleships that were there were damaged. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft ship, and one minelaying ship. 188 U.S. aircraft were destroyed, 2,402 personnel were killed and 1,282 were wounded. The power station, shipyard, maintenance, and fuel and torpedo storage facilities, along with the submarine piers and headquarters building were not attacked. Japanese losses were light, with 29 aircraft and five submarines lost, and 65 servicemen killed or wounded(most were Kamikazes and pilots). One Japanese sailor was captured. The cause for the great amount of airplanes lost was because they were parked "wingtip to wingtip", and this made it easy for the Japanese to destroy many American airplanes.

The attack was a major engagement of World War II and came as an unbelievable event to the American people. Domestic support for isolationism, which had been strong, disappeared. The U.S. showed great support of Britain and the rest of the Allied Forces and moved into active alliance and full participation in the European Theater. Despite numerous historical precedents for unannounced military action, the lack of any formal warning by Japan, particularly while negotiations were still apparently ongoing, led to it being characterized as a "sneak attack", and to President Franklin D. Roosevelt proclaiming December 7 "a day which will live in infamy". This was also a direct cause of the United States entry into WWII.
Map of Japanese attack routes and positions
Map of Japanese attack routes and positions