Attack on Pearl Harbor

battle_name=Attack on Pearl Harbor

Japanese preparations

Japan had seized Manchuria in 1931, and had been fighting the Second Sino-Japanese War with China since 1937. During 1941 the long-standing tensions between the Japanese Empire and the United States resulting from these military adventures were rising. The United States and the United Kingdom reacted to Japanese military actions in China by imposing a scrap metal boycott followed by an oil boycott, a freeze of assets and the closing of the Panama Canal to Japanese shipping. Diplomatic negotiations climaxed with the Hull note of November 26th, 1941, which Prime Minister Hideki Tojo described to his cabinet as an ultimatum. The oil boycott was especially threatening to Japan, which lacked oil resources of its own. The Japanese leaders decided they had only three choices: give in to the demands of the USA and the UK and back out of China, wait for a lack of fuel to cripple their military, or escalate the conflict to try and acquire sources of oil in Southeast Asia. They chose the latter.

Related Topics:
Manchuria - 1931 - Second Sino-Japanese War - China - 1937 - United Kingdom - Panama Canal - Hull note - November 26th - 1941 - Hideki Tojo - Ultimatum

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The Japanese had been tremendously impressed with Admiral Andrew Cunningham's Operation Slapdash (the Battle of Taranto), where a few antique biplanes launched from a carrier force way in advance of the main British base at Alexandria disabled half the Italian battlefleet and forced the withdrawal of the Italian fleet to behind Naples. Yamamoto dispatched a naval delegation to Italy, which concluded a larger and better supported version of Cunningham's brilliant maneuver could force the U.S. fleet back to California, giving time to achieve the "Greater East Asia Co-Prosperity Sphere"—shorthand for control of the oil reserves of the Dutch East Indies, with a defensible buffer around them. Most importantly, the delegation returned to Japan with the secret of the shallow running torpedo which Cunningham's "boffins" had devised.

Related Topics:
Andrew Cunningham - Battle of Taranto - Dutch East Indies

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Additionally, the Japanese may have been influenced by the actions of U.S. Admiral Harry Yarnell in the 1932 joint Army-Navy exercises, which presumed an invasion of Hawaii by hostile forces. Yarnell, in the role of the commander of the attacking fleet, sailed his aircraft carriers northwest of Oahu into rough weather, and launched attack planes on the morning of Sunday, 7 February 1932. "Judges" assigned to gauge the effectiveness of the attack noted that Yarnell's aircraft were able to inflict serious damage on the defenders, who were unable to locate his fleet 24 hours after the attack. Conventional Navy doctrine of the time believed that any attacking force would be set upon and destroyed by the battleship fleet stationed at Pearl Harbor, and dismissed Yarnell's strategy and attack.

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The aim of the attack on Pearl Harbor was to neutralize American naval power in the Pacific, if only temporarily, as part of a theater-wide, near-simultaneous coordinated attack. Admiral Yamamoto Isoroku himself suggested that even a successful attack would gain only a year or so of freedom of action. Planning for an attack in support of further military advances began in January 1941, and training for the mission was under way by mid-year when the project was finally judged worthwhile after some Imperial Navy infighting. The attack depended on torpedoes, but the weapons of the time required deep water when air launched. Over the summer of 1941, Japan secretly created and tested torpedoes that could be launched in shallow Pearl Harbor. The effort resulted in the Type 95 torpedo that inflicted the majority of the damage to U.S. ships. Japanese weapons technicians also produced special armor-piercing bombs by fitting fins on 14 and 15-inch naval gun shells. Dropped from 10,000 feet, they would be able to penetrate the armored decks of the American battleships and cruisers moored in Pearl Harbor.

Related Topics:
American naval power - Theater - Yamamoto Isoroku - Type 95 torpedo

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On November 26 1941, a fleet including six aircraft carriers commanded by Japanese Vice Admiral Chuichi Nagumo left Hitokappu Bay in the Kuril Islands under strict radio silence bound for Hawaii. The aircraft carriers involved in the attack were: Akagi, Hiryu, Kaga, Shokaku, Soryu, and Zuikaku. Escorting the task force were 2 fast battleships, 2 heavy cruisers, 1 light cruiser, 9 destroyers, and 3 fleet submarines. The carriers had a total of 423 planes, including Mitsubishi Type 0 "Zero" fighters, Nakajima Type 97 "Kate" torpedo bombers, and Aichi Type 99 "Val" dive bombers. The Japanese task force and its air group was larger than any previous aerial strike force. Accompanying the fleet were 8 tankers for underway refueling. In addition, the Advanced Expeditionary Force comprised of 20 fleet submarines and 5 2-man Ko-hyoteki-class midget submarines was sent to Hawaiian waters to gather intelligence and sink any U.S. vessels that might try to flee Pearl Harbor during the air attack.

Related Topics:
November 26 - 1941 - Aircraft carrier - Chuichi Nagumo - Hitokappu Bay - Kuril Islands - Radio - ''Akagi'' - ''Hiryu'' - ''Kaga'' - ''Shokaku'' - ''Soryu'' - ''Zuikaku'' - Battleship - Heavy cruiser - Destroyer - Fleet submarine - Mitsubishi Type 0 - Fighter - Nakajima Type 97 - Torpedo bomber - Aichi Type 99 - Dive bomber - Tanker - Ko-hyoteki-class - Midget submarine

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