USS R-4

USS R-4 (SS-81) was one of 27 R-class coastal defense submarines built for the United States Navy during World War I. Ordered in 1917 and commissioned in 1919, R-4 saw no active combat service during the war.

After commissioning, R-4 operated primarily along the Atlantic coast, participating in training exercises and fleet maneuvers. A significant portion of her service was devoted to experimental work, contributing to the development of submarine warfare tactics and technology. This included testing new torpedoes, sonar equipment, and communication methods.

R-4 had a relatively short service life. She was decommissioned on 24 October 1924 at Coco Solo, Panama Canal Zone, and struck from the Naval Vessel Register on 9 May 1930. On 25 September 1930, she was sold.