In October 1870, he was appointed a second lieutenant in the Marine Corps by the President of the United States. Second Lieutenant Elliott served at the Marine Barracks, Washington, D.C., from the time of his appointment to the Marine Corps until 1871, when he was transferred to Portsmouth, New Hampshire. He later served on , , and , and was on duty at the Marine Barracks at Norfolk, Virginia, in 1877 when a battalion of Marines was ordered to that post from Washington, D.C. during the strike of railway employees. He was in command of the detachment that guarded the Baltimore and Ohio Railroad tunnel and also acted as guard for the paymaster of the railroad. He returned to Norfolk upon detachment from that duty. He was promoted to first lieutenant in 1878.