In September 1944, to prevent Japanese air interdiction against General MacArthur's planned invasion of the Southern Philippines, the Americans attacked Peleliu and Angaur in the Palau group of the Western Caroline Islands. Admiral Halsey, commanding the US Third Fleet, feared the heavily defended Palaus would be costly for his III Amphibious Corps comprising the 1st Marine Division and the 81st Infantry Division. While Angaur fell in four days, on Peleliu the Japanese resisted tenaciously using their underground fortifications on the Umurbrogel Ridge overlooking the airfield. It was only after over two months' bitter fighting that the Americans finally controlled the Island. Despite the heavy cost, the benefits of this hard fought and costly victory were doubtful. In the event, Mindanao and other Southern Philippine Islands were bypassed by MacArthur in favour of a direct assault on Leyte on 20 October. But, as the graphic images and well researched text bear witness, there is no denying the courage and determination shown by the attacking US forces.