On 15 September 1944, United States Marine Corps forces landed on the southwestern shore of the island of Peleliu in the Palau island chain, 470 nautical miles due east of the Philippine island of Mindanao. This action, called Operation Stalemate II by American planners, was a phase in the Pacific Theatre of World War II. Whether possession of the island was necessary for the Allied cause has been the source of much controversy.