Taplett was dispatched to Korea immediately after the outbreak of hostilities. He was made commanding officer of the 3rd Battalion, 5th Marines, and participated in numerous battles. His unit held the perimeter at Pusan and led the Inchon landing, taking Wolmi-do Island(Battle of Inchon), which was the gateway to Inchon. He led the 3rd Battalion through the gates of Seoul to liberate the South Korean State House.