Welles gave 33 years service to the navy in a variety of placements, eventually being promoted to Rear-Admiral. As an ensign he was engaged in surveys in Alaska, where he made a study of native peoples culture and language in his spare time. He served two years in the post of Special Counsel to the World's Columbian Exposition in Chicago, and was awarded by its board for research on Orinoco River Indians. A former commander of the Naval Training Center in Newport, his command of the Oklahoma was a short period of time mainly involving the command as a training ship. This was because the oil-fired boilers that she used were not able to be fueled in England, as German U-boats had drained their supply. After he gave command over to Rear Admiral Spencer K. Wood, he was appointed Director of the Office of Naval Intelligence (April 1917 – January 1919).
Welles married Harriet Deen Gardner on 17 October 1908, who followed her husband's ship to Asia and later published accounts of journeys in Scribner's Magazine and the popular book Anchors Aweigh. He was entered on the Navy's Retired List on 7 December 1926, upon attaining the age of 64, and died in New York on 26 April 1932.
|Wikisource has original works written by or about:
- Phister, Jeff; Hone, Thomas; Goodyear, Paul (2008). Battleship Oklahoma, BB-37 (2008 ed.). University of Oklahoma Press. ISBN 978-0-8061-3917-3.
- Linder, Bruce (Spring 2003). "Rear Admiral Roger Welles—San Diego's First "Navy Mayor"". The Journal of San Diego History. 49 (2).
- Phister-Hone-Goodyear p. 31
- Persico, Joseph E. (2002). Roosevelt's Secret War: FDR and World War II Espionage (2002 ed.). Random House. ISBN 978-0-375-76126-3.