After completion at the Boston Navy Yard, "R-5" got underway on 28 April 1919 for New London, Connecticut, where she was assigned to Submarine Division 9 of the Atlantic Fleet. She headed south on 4 December for Norfolk, Virginia, and winter exercises with her division in the Gulf of Mexico from 21 January to 14 April 1920. "R-5" later returned to Newport, Rhode Island, on 18 May for four months of summer training in New England waters. Then given hull classification symbol SS-82 (effective 17 July) she sailed 13 September for Norfolk and an overhaul that was completed in April 1921.