The USS Gagarin (NCC-1309) was a Federation Shepard-class starship operated by Starfleet during the mid-23rd century. In 2256, this ship was commanded by Captain T'Shen Kovil.
During the Federation-Klingon War, this ship was in the same sector as the USS Hoover and the USS Muroc when they were simultaneously ambushed by Klingons. The Gagarin faced six warships.
After losing warp drive, Kovil sent a distress call, to which the USS Discovery responded. The Discovery attempted to relieve the pressure on the Gagarin, but was unable to interdict a torpedo fired by a Bird-of-Prey that destroyed the Gagarin with all hands. The loss of the three Federation starships resulted in 462 Starfleet casualties. (DIS: "Si Vis Pacem, Para Bellum")