He served as Commandant of the Washington Navy Yard and Superintendent of the Naval Gun Factory from 1915 to early 1917 when he was appointed the Navy Department representative in a special mission under Elihu Root sent to Russia. At the risk of his life, he persuaded mutinous Russian sailors who had taken over command of Russian ships-of-war in waters of Sevastapol, to restore authority to the officers of the men-of-war. After completing the mission to Russia, he took command of Battleship Division 5 with his flag in battleship Connecticut. He was awarded the Navy Cross for meritorious service in this command, including the instruction of midshipmen and thousands of recruits for duty as armed guard crews of merchant ships.
Detached from this duty on 17 September 1918, he became Commandant of the 13th Naval District until 3 January 1919, then was Commandant of the 3d Naval District at New York. Having reached the statutory age for retirement, he was transferred to the Retired List on 1 February 1921.
Rear Admiral Glennon died at Washington, D.C., 29 May 1940.
Source: Naval History & Heritage Command including Dictionary of American Naval Fighting Ships.