After returning to the fleet, "Mississippi" provided gunfire support for the Marines that went ashore at Peleliu, bombarding Japanese positions on 12 September, three days before the landing. She remained there, shelling the island for a week, before proceeding on to Manus, which had recently been taken by American forces. Assigned to the invasion fleet for the Philippines under Rear Admiral Jesse B. Oldendorf, "Mississippi" left Manus on 12 October and arrived off Leyte on the 19th, when she began the coastal bombardment. During the Battle of Leyte Gulf, on the night of 24 October, "Mississippi" and the rest of the coastal bombardment battleships decisively defeated the Japanese Southern Force under Vice Admiral Shōji Nishimura in the Battle of Surigao Strait. During the battle, the Japanese warships failed to detect the American vessels with their radar. Additionally, the narrow strait forced the Japanese to steam in line ahead, while "Mississippi" and the other battleships were stationed at the entrance, where they were able to fire full broadsides. As a result, Nishimura was unable to avoid having his "T" crossed. In the ensuing action, American destroyers inflicted heavy damage on the Japanese force, which was then annihilated by the concentrated fire from the battleships. "Mississippi", which was equipped with older fire control radar, had trouble identifying targets in the darkness, and so fired only one 12-gun salvo, after Oldendorf had given the order to cease fire. This salvo was the last fired in the action, and proved to be the last time a battleship fired its guns at another battleship.