The landing on Leyte on 17 October triggered the Japanese high command to initiate Operation "Shō-Gō" 1, a complicated counter-thrust that involved four separate fleets converging on the Allied invasion fleet to destroy it. The 1st Mobile Fleet, now labeled the Northern Force, had been significantly reduced in strength by three years of combat and was intended to serve only as a distraction to lure the American fast carrier task force away from the invasion fleet. Meanwhile, Vice Admiral Takeo Kurita's Center Force would pass through the San Bernardino Strait and attack the invasion fleet. The Americans detected Kurita's approach, however, and the carriers launched a major attack on his fleet while it passed through the Sibuyan Sea. After losing the powerful battleship in the Battle of the Sibuyan Sea on 24 October, Kurita temporarily reversed course. This convinced Halsey, now the commander of Third Fleet, to send the fast carrier task force to destroy the 1st Mobile Fleet, which had by then been detected.