Johnston graduated from the United States Military Academy in 1879, graduating twenty-third out of sixty seven.Davis, Henry Blaine Jr. Generals in Khaki (Raleigh, NC: Pentland press, 1998), p. 205 He was commissioned into the cavalry and performed frontier duty in Texas from 1879 to 1882. In 1883, he was an honor graduate from the Infantry and Cavalry School at Fort Leavenworth, Kansas, after which he became an instructor there, instructing on the art of war and engineering until 1885.Who Was Who in American History – The Military (Chicago, IL: Marquis Who's Who, Inc., 1975) p. 292
