Carleton was an 1881 graduate of the United States Military Academy; assigned to the Cavalry, he served throughout the west during the last of the American Indian Wars. He was a veteran of the Spanish–American War, the Philippine–American War, and the Veracruz Expedition. During World War I, he commanded Camp Zachary Taylor, Kentucky and the 159th Depot Brigade, followed by Camp Wadsworth, South Carolina and the 96th Division, and then Camp Kearny, California and the 16th Division. After the war, Carleton commanded Camp Lewis, Washington and the 166th Depot Brigade.