support an air campaign against the Australian and American forces stationed at Port Moresby. Between April and July, the Tainan Air Group flew 51 missions, totalling 602 sorties. During this time, the unit claimed to have destroyed 300 enemy aircraft. The Tainan's losses were 20 aircraft. Replacement aircraft gave the unit a total of 24 Zeros by August 1942, flown by 55 pilots. Because of the surplus in aircrew, only the most experienced pilots were allowed to fly combat missions. Guadalcanal On August 7, United States Marines landed on Japanese-occupied Guadalcanal, initiating the Guadalcanal Campaign. In response that same day, 18 Tainan fighters escorted bombers from Rabaul for an attack on the Allied invasion fleet, the longest fighter mission of the war (556 miles each way) to that date. The Tainan claimed to have destroyed 43 enemy aircraft over Guadalcanal on that mission while losing two fighters with their pilots themselves. The Americans actually lost 10 aircraft, including nine of 18 fighters present, plus one dive bomber. The two Tainan pilots killed on this mission were Petty Officer First Class Yoshida and Petty Officer Second Class Nishiura One significant Tainan casualty over Guadalcanal that day was Saburō Sakai, who was seriously injured and forced into a two-year recuperation. The US Marines on August 8 captured an airfield (later called Henderson Field) under construction by the Japanese on Guadalcanal which was soon operational with Allied aircraft. Over the next several months, Tainan aircraft based at Rabaul engaged in repeated dogfights with Allied aircraft, called the Cactus Air Force, based on Guadalcanal. The extreme distances required for the Tainan pilots to fly from Rabaul to Guadalcanal severely hampered the unit's attempts to establish air superiority over the island. The unit also continued to support bombing missions against Port Moresby. Between August and November 1942, the Tainan lost 32 pilots killed in action. Junichi Sasai was killed on August 26 and Toshio Ōta on October 21. On November 1, 1942 the Japanese naval units in the Southeast Pacific were reorganized. The Tainan was redesignated as the 251 Air Group and reconstituted with replacement aircrews. The 20 surviving pilots of the Tainan were transferred to Japan to help form new fighter units. Bergerud says only 10 pilots were left and that the new unit was not called the "251st Air Group". Each digit in "251" refers to a discrete attribute of the new organization.