During the Mariana Islands campaign, US forces captured Japanese-held islands in the Battles of Guam, Saipan and Tinian between June and August 1944. USAAF and US Navy engineers subsequently constructed six airfields on the islands to accommodate hundreds of B-29s. These bases were more capable of supporting an intensive air campaign against Japan than those in China as they could be easily supplied by sea and were south of Tokyo, which allowed B-29s to strike most areas in the home islands and return without refueling. Japanese aircraft made several attacks on the airfield at Saipan while it was under construction.