Later that year, the Eagle, along with the USS Excelsior and the USS Potemkin, was selected for the primary operational phase of the abandoned rescue mission code-named "Operation Retrieve", which would have rescued Captain James Kirk and Doctor Leonard McCoy from Rura Penthe in 2293. According to the plans, the Eagle was to provide protection on the Potemkin's port flank as this ship retrieved the two Starfleet officers. (Star Trek VI: The Undiscovered Country)
|USS Ahwahnee • USS Constellation • USS Defiant • USS Eagle • USS Emden • USS Endeavour • USS Enterprise • USS Enterprise-A • USS Excalibur • USS Exeter • USS Hood • USS Intrepid • USS Korolev • USS Lexington • USS Potemkin • NCC-1700 • Unnamed|
|Mirror universe: USS Defiant • ISS Enterprise|
|Alternate reality: USS Enterprise • USS Enterprise-A • Unnamed|
This starship and registry number were not referenced in dialogue. This vessel appeared in the plans for Operation Retrieve presented by Colonel West. Save for the USS Excelsior, the Eagle and five other starships were graphically represented by the silhouette of a movie era refit-Constitution-class vessel. Michael Okuda, the creator of the charts, usually endowed Constitution-class vessels that had not yet been provided with one canonically with numbers either derived from Franz Joseph's reference book Star Trek Star Fleet Technical Manual (NCC-1719) or Greg Jein's influential "The Case of Jonathan Doe Starship" article (NCC-1685), published in the April 1973 issue 27 of the T-Negative fanzine. In this case though, Okuda deviated from the norm and used a number originating from neither. Okuda has stated years later, "In still other cases, the ships and/or numbers did not come from either source, but were consistent with some fleet status charts I did elsewhere on the USS Enterprise-A in Star Trek VI."  Okuda has since then propagated the number throughout his subsequent reference book writings.
From this, Okuda's Star Trek Encyclopedia (4th ed., vol. 2, p. 328) listed the ship as a Constitution-class vessel.
The name of the ship had been considered by producer Robert Justman at the start of second season of Star Trek: The Original Series for inclusion in the definitive list of fourteen ships belonging to the Constitution-class, still referred to as "Starship-class" by them at the time. It was mentioned in the second proposal, but ultimately did not make the cut. His suggestion of 9 August 1967 even made it onto page 64 of the first draft treatment of the script, dated September 30, 1967 for the second season episode "Journey to Babel", which contained a line having Lieutenant Uhura state,
- "Star Fleet Command confirms alien attack on the other starships, sir. The enemy was defeated. Starships Essex and Eagle suffered heavy damage, but will make base."
The reference though, was dropped from the episode as aired.  Justman also annotated on his proposal memo, "I think there would be several other candidates, such as Saratoga and perhaps another English carrier, a French carrier, a Russian carrier and certainly a Japanese carrier." Had his suggestion made the final cut, then the historical British aircraft carrier HMS Eagle would have footed the bill. (The Making of Star Trek, pp. 164-165)
An unseen element from the Operation Retrieve charts included a list of starships, their registries and their commanders. According to this list, the Eagle was commanded by K. Garretson,  named for Katy E. Garretson, who served as second assistant director on The Undiscovered Country.
The Andorians: Among the Clans by S. John Ross featured a listing of a Constitution-class USS Eagle with the registry NCC-956 listed in the Star Trek Encyclopedia and the chart seen the Federation President's office in Star Trek VI: The Undiscovered Country. In the Andorian language invented by Ross it was known as the USS Atlirith (an Andorian eagle).