Attack on Pearl Harbor
The attack commenced at 7:48 a.m. Hawaiian Time (18:18 GMT). The base was attacked by 353 Imperial Japanese aircraft (including fighters, level and dive bombers, and torpedo bombers) in two waves, launched from six aircraft carriers. All eight U.S. Navy battleships were damaged, with four sunk. All but were later raised, and six were returned to service and went on to fight in the war. The Japanese also sank or damaged three cruisers, three destroyers, an anti-aircraft training ship, and one minelayer. 188 U.S. aircraft were destroyed; 2,403 Americans were killed and 1,178 others were wounded. Important base installations such as the power station, dry dock, shipyard, maintenance, and fuel and torpedo storage facilities, as well as the submarine piers and headquarters building (also home of the intelligence section), were not attacked. Japanese losses were light: 29 aircraft and five midget submarines lost, and 64 servicemen killed. One Japanese sailor, Kazuo Sakamaki, was captured.
Nuclear warfare
In late June 1945, as the U.S. wrapped up the two-and-a-half-month Battle of Okinawa (which cost the lives of 260,000 people, including 150,000 civilians), it was faced with the prospect of invading the Japanese home islands in an operation codenamed Operation Downfall. Based on the U.S. casualties from the preceding island-hopping campaigns, American commanders estimated that between 50,000 and 500,000 U.S. troops would die and at least 600,000–1,000,000 others would be injured while invading the Japanese home islands. The U.S. manufacture of 500,000 Purple Hearts from the anticipated high level of casualties during the U.S. invasion of Japan gave a demonstration of how deadly and costly it would be. President Harry S. Truman realized he could not afford such a horrendous casualty rate, especially since over 400,000 American combatants had already died fighting in both the European and the Pacific theaters of the war.