 Tweed enlisted in the United States Navy in 1922 and attended the basic training at Naval Station Great Lakes.He also attended the Radioman School and served in the various Navy radio units until 1940, when he was transferred to the Naval Base Guam.At the time a 16-year veteran of the Navy with the rank of Radioman First Class, Tweed was serving in the Navy Communication Office when the Japanese invaded the island on December 8, 1941, in the First Battle of Guam.