Established on 14 July 1942, the IJN 8th Fleet was a headquarters unit established to direct Japanese naval operations in the Solomon Islands and New Guinea. The warship forces assigned to the 8th Fleet were known as the Outer South Seas Force and Vice Admiral Gunichi Mikawa was assigned as the first commander. From December 20, 1942 until the end of the war, the IJN 8th Fleet came under the operational authority of the Southeast Area Fleet. Its headquarters staff was later isolated on Bougainville Island with remnants of Imperial Japanese Army forces at the end of the war.