 He entered the University of Georgia (UGA) in Athens in 1869; however, he left UGA before graduating to accept an appointment to the United States Military Academy.He graduated from the academy in 1876 and was commissioned on June 15 of that year as a second lieutenant in the 7th Regiment of the United States Cavalry, but he did not physically join the unit until after the Battle of the Little Big Horn, which occurred several weeks after his appointment.Due to his regiment's heavy losses, Garlington was quickly promoted to first lieutenant on June 25, 1876 and then to Regimental Adjutant June 6, 1877, and served in that post until 1881.