For the next year and a half, Carlin commanded the 2nd Brigade, 1st Division of the XX Corps. He participated in the Tullahoma Campaign and the subsequent Battle of Chickamauga. In the autumn of 1863, he fought at Lookout Mountain and Missionary Ridge during the Battles for Chattanooga. In the summer of 1864, he led his brigade in the Atlanta Campaign, taking a brief furlough during the campaign to return to Illinois to be married. He was promoted to divisional command before the Battle of Jonesboro in September. He then took part in Sherman's March to the Sea and the capture of Savannah, Georgia.