McCain returned to combat in the Pacific in August 1944 with his appointment as commander of a carrier group in Marc Mitscher's Task Force 58 (TF 58), part of Raymond Spruance's Fifth Fleet. In this role, McCain participated in the Marianas campaign, including the Battle of the Philippine Sea, and the beginning of the Philippines campaign. At the Battle of Leyte Gulf, Admiral William Halsey left in pursuit of a decoy force, leaving Rear Admiral Clifton "Ziggy" Sprague's Task Unit 77.4.3 (usually referred to by its radio callsign, "Taffy 3") to continue supporting forces ashore, defended by only a light screen of destroyers and destroyer escorts.