Oates participated in the battles of Chickamauga, the Wilderness, Spotsylvania Court House, and Cold Harbor. After losing command of his colonelcy of the 15th Alabama because of a political move, he was made colonel of the 48th Alabama by Confederate President Jefferson Davis. Oates was wounded during the Battle of Fussell's Mill on the outskirts of Richmond, losing his right arm, which ended his active service.