Pearl Harbor Attack | Date, History, Map, Casualties, Timeline, & Facts

Prelude to war

In the late 1930s, American foreign policy in the Pacific hinged on support for China, and aggression against China by the Empire of Japan therefore necessarily would bring Japan into conflict with the United States. As early as 1931 the Tokyo government had extended its control over the Chinese province of Manchuria, and the following year the Japanese cemented their hold on the region with the creation of the puppet state of Manchukuo. A clash at the Marco Polo Bridge near Beijing on July 7, 1937, signaled the beginning of open warfare between Japan and the United Front of Chinese Nationalists and the Chinese Communist Party. In response, the United States government extended its first loan to China in 1938.

In July 1939 the U.S. announced the termination of the 1911 Treaty of Commerce and Navigation with Japan. Beginning in the summer of 1940, the U.S. began to restrict the export to Japan of materials useful in war. Between June 1940 and the fateful crisis of December 1941, the tension constantly mounted. In July 1941, by which time the Japanese had occupied all of Indochina and had entered into an alliance with the Axis powers (Germany and Italy), the U.S. government severed all commercial and financial relations with Japan. Japanese assets were frozen, and an embargo was declared on shipments to Japan of petroleum and other vital war materials. Militarists were steadily gaining in influence in the Tokyo government; they bitterly resented U.S. aid to China, which by this time had been stepped up. They saw in the German invasion of the Soviet Union an unrivaled opportunity to pursue a policy of aggression in the Far East without danger of an attack upon their rear by the forces of the Red Army. Nonetheless, negotiations looking to find some kind of understanding between the United States and Japan took place through the autumn of 1941, and not until near the end of November did it become clear that no agreement was possible.

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Although Japan continued to negotiate with the United States up to the day of the Pearl Harbor attack, the government of Prime Minister Tōjō Hideki decided on war. Adm. Yamamoto Isoroku, the commander in chief of Japan’s Combined Fleet, had planned the attack against the U.S. Pacific Fleet with great care. Once the U.S. fleet was out of action, the way for the unhindered Japanese conquest of all of Southeast Asia and the Indonesian archipelago would be open. The order for the assault was issued on November 5, 1941, and on November 16 the task force began its rendezvous in the Kuril Islands. Commanders were instructed that the fleet might be recalled, however, in case of a favorable outcome of the negotiations in Washington, D.C. On November 26, Vice Adm. Nagumo Chuichi led a fleet including 6 aircraft carriers, 2 battleships, 3 cruisers, and 11 destroyers to a point some 275 miles (440 km) north of Hawaii. From there about 360 planes in total were launched.