There was a 15th Missouri Cavalry Regiment in U.S. service, but the regiment in which Lieutenant McCarley served was a Confederate regiment. The 15th Missouri Cavalry (Confederate) recruited heavily in northeast Arkansas. Perhaps as many as half the men in the regiment were from Arkansas. In addition to Thomas P. McCarley, a Pvt. William McCarley, of Randolph County, Arkansas, also served in this regiment. Both men were paroled at Jacksonport on June 5, 1865.