1941 - 1945: US R Class
The R class submarines were a class of United States Navy submarines active from 1918 until 1945.
R-1 to R-20 built by Fore River Shipyard and Union Iron Works (R1 Class).
The R-boats R-21 to R-27, built by Lake Torpedo Boat, slightly smaller and faster than the others, are sometimes regarded as a separate class (R-21 class)