The USS Emden (NCC-1856) was a Constitution-class Federation starship in service in the 23rd century. (Trekmania) In 2293, the Emden was one of many starships that were to form part of Starfleet's "Operation: Retrieve": A daring rescue plan to bring Captain James T. Kirk and Dr. Leonard McCoy home from the Klingon Empire after the assassination of Chancellor Gorkon. (Star Trek VI: The Undiscovered Country)