"Lapon" sailed for the South China Sea on 4 September, Lieutenant Commander (LCDR) Donald G. Baer in command. She rendezvoused with submarines and and became a member of a wolfpack. Early in the morning of 21 September, the submarine contacted an enemy hospital ship and allowed the ship to pass unharmed. That afternoon, while rounding Palauic point, "Lapon" spotted smoke and commenced closing. As she neared attack position U.S. carrier-based planes attacked the convoy, inflicting heavy damage on the enemy. "Lapon" attacked remnants of the convoy 22 September and sank the cargo ship "Shun Yuan". The next day "Flasher" and "Lapon" made a coordinated attack on several ships, "Lapon" sinking the tanker "Hokki Maru". Patrolling off the coast of Luzon 10 October 1944, "Lapon" intercepted a Manila-bound convoy and sank the cargo ship "Ejiri Maru". Assigned to lifeguard duty, the submarine was on station during the air attacks preliminary to the invasion of the Philippines; and 21 October departed for Australia, arriving at Fremantle 31 October.