page_title: Combined Fleet
section_title: World War II
hierarchical_section_title: Combined Fleet / History / World War II
caption_attribution_description: portrait of Isoroku Yamamoto
context_page_description: Combined Fleet was the main sea-going component of the Imperial Japanese Navy. Until 1933, Combined Fleet was not a permanent organization, but a temporary force formed for the duration of a conflict or major naval maneuvers from various units normally under separate commands in peacetime.
context_section_description: Combined Fleet came under direct command of the Imperial General Headquarters in 1937. With the start of the Pacific War with the attack on Pearl Harbor carried out by Combined Fleet's Kido Butai (1st Air Fleet), Combined Fleet became almost synonymous with the Imperial Japanese Navy.  It comprised the battleships, aircraft carriers, aircraft, and the components that made up the main fighting strength of the IJN. It was first mobilized on the whole for the Battle of Midway.  After the devastating carrier losses at Midway and in the Solomon Islands campaign, the navy re-organized into a number of "Area Fleets" for local operational control of various geographic zones. Combined Fleet then evolved into more of an administrative organization.
  As the war situation deteriorated for the Japanese and the territories controlled by the "Area Fleets" fell one after another to the United States Navy, the Imperial General Headquarters and the Imperial Japanese Navy General Staff acted to force the American fleet into a "decisive battle" in the Philippines per the kantai kessen philosophy.  In the resultant Battle of the Philippine Sea and the Battle of Leyte Gulf the Japanese fleet was severely depleted.  The remnants of Combined Fleet fled to Okinawa, but further operations were hindered by lack of fuel and air cover.  By the time of the final suicide mission of the battleship Yamato in Operation Ten-Go, Combined Fleet had ceased to exist as an effective combat force.
caption: Admiral Isoroku Yamamoto, commander-in-chief of Combined Fleet during the early stage of the Pacific War.
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