On 21 May 1908, he was appointed Major General Commandant of the Marine Corps. One of the most difficult endeavors of General Elliott's career was his successful resistance to attempts to remove seagoing Marines from capital ships and to merge the Corps into the Army. Also during his tenure, the home post of the Corps, the Marine Barracks at 8th and I Streets SE in Washington, D.C., underwent major changes. In 1903, the old barracks were condemned and pulled down and by 1910 had been rebuilt essentially in their present form. He was placed on the retired list on 30 November 1910 upon reaching the statutory retirement age.