By May 1945, as bitter fighting continued on Okinawa and Americans celebrated Germany's surrender, Pacific strategists had developed detailed plans for Operation Downfall, the two-phased invasion of the Japanese home islands to begin on 1 November. More than 5 million Allied troops would conduct the two largest planned amphibious assaults in history. As planned, all six Marine divisions and three Marine aircraft wings would play major combat roles.
The Japanese defensive plan for Kyushu encompassed three phases. First, thousands of suicide aircraft and boats would attack the American fleet, targeting troop transports in an effort to disrupt the landings. Second, newly organized defense divisions occupying heavy fortifications overlooking the beaches, would attempt to prevent the landing force from gaining a foothold. Finally, mobile divisions based inland would counterattack toward threatened positions. In August 1945, Japanese ground forces on Kyushu consisted of 14 divisions and several independent brigades, about 600,000 die-hard troops, most of whom were deployed near the invasion area.