(Submarine No. 81: displacement 569 (surfaced), 680 (submerged); length 186-2-; beam 18-; draft 14-6- (mean); speed 13.5 knots (surfaced), 10.5 knots (submerged); complement 34; armament 1 3-, 4 21- torpedo tubes; class R-1)
R-4 (Submarine No. 81) was laid down 16 October 1917 by the Fore River Shipbuilding Co., Quincy, Mass.; launched 26 October 1918; sponsored by Mrs. Albert W. Stahl; and commissioned 28 March 1919, Lt. Palmer Hall Dunbar, Jr. in command.
After outfitting at Boston Navy Yard, R-4 joined Submarine Division 9 of the Atlantic Fleet at New London, Conn., 12 August 1919. She sailed 4 December 1919 for Norfolk and winter operations in the Gulf of Mexico from 21 January to 14 April 1920. R-4 later returned to New England 18 May for 4 months of maneuvers with her division. Designated SS-81 in July, she arrived at Norfolk 15 September for an overhaul lasting until April 1921.
R-4 deployed to the Pacific 11 April 1921, transited the Panama Canal 28 May, and arrived at her new base, San Pedro, Calif., 30 June. She participated in war games with the battle fleet in the Gulf of Fonseca, 5 February to 6 April 1923, returning to San Pedro with Camden (AS-6) 10 April. R-4 was transferred 16 July with Division 9 and Canopus (AS-9) to Pearl Harbor where she remained for the next 8 years engaged in training and operations with fleet units.
R-4, ordered back to the Atlantic with Divisions 9 and 14 on 12 December 1930, transited the Panama Canal 18 January 1931, and arrived 9 February at New London. She was soon assigned to Division 4 and served as training ship for the next 10 years on rotating duty between the New London Submarine School and the Yale University NROTC unit. R-4 departed New London 26 May 1941 for Key West, Fla. and Patrol duty in the Florida Straits with Division 12. Back at New London for the first 2 weeks in July, she returned to Key West at midmonth and until March of 1945 alternated duties for the Fleet Sonar School with patrols in the Florida Straits and the Yucatan Channel.
At Port Everglades 11 March to 15 April 1945, R-4 returned to Key West to prepare for inactivation. On 1 June she was withdrawn from active duty and on the 4th she got underway for Philadelphia. Escorted by SC-1001 she arrived at Philadelphia 8 June, decommissioned on the 18th and was struck from the Navy list 11 July. The following January, 1946, she was sold for scrap to the North American Smelting Co.