After graduating from the Naval Academy in 1923 and earning his MA in Eengineering from Penn State in 1930, Smoot served in the submarine USS Narwhal (SS-167) until 1933. During World War II he was CO of the USS Monssen (DD-436), which was one of the escort ships for the USS Hornet (CV-8) transporting Colonel Jimmy Doolittle's flyers for their famous 1942 strike on Tokyo. His ship later participated in the Battle of Midway; assault and occupation of Guadalcanal; the first Battle of Savo Island; and the Battle of the Eastern Solomons. In 1944 he was Commander Destroyer Squadron 56 involved in the Battle of Surigao Strait and the assault on Iwo Jima. His later career included duty as CO Newport News; Commander Cruiser Division Three; Commander Mine Force, U.S. Pacific Fleet; and Commander, U.S. Taiwan Defense Command.