By 1863, Elder's battery was assigned to the U.S. Horse Artillery Brigade, where it served for most of the remainder of the war. He earned a permanent promotion to captain on August 1, 1863. Detached briefly in February 1864, Elder was cited for gallantry at the Battle of Olustee in Florida, and was awarded the brevet promotion to major. Returning to the Horse Artillery, he was again cited for actions at Drewry’s Bluff, May 5, 1864, and was brevetted lieutenant colonel. He remained with the Army after the war, and was promoted to major in the 2nd U.S. Artillery, June 30, 1882.