Operation Retrieve was the code name of a mission proposed by Starfleet Colonel West upon the arrest of Captain James T. Kirk and Doctor Leonard McCoy for the assassination of Chancellor Gorkon in 2293. It was devised, in light of increasing tensions between the United Federation of Planets and the Klingon Empire, to extricate the officers from their captivity by military force.
The details of the operation involved a direct incursion by several starships launched from Starbase 24 to the penal world of Rura Penthe, well within Klingon territory, and was expected to last no more than 24 hours with an acceptable loss to equipment and manpower.
The plan was vetoed by the Federation President as it would have most likely provoked the Klingon Empire into a full scale war. The operation was subsequently proven to be unnecessary, as the USS Enterprise-A entered Klingon space without authorization from Starfleet and retrieved Kirk and McCoy from the planet. (Star Trek VI: The Undiscovered Country)
The Operation Retrieve briefing material had a fourth page that was never seen on-screen, and is reproduced to the right.