A peace treaty between the Federation and Klingons.
The Khitomer Accords were the peace treaty between the Federation and the Klingon Empire agreed at the end of Star Trek VI: The Undiscovered Country in 2293. They followed the destruction of Praxis, which forced the Empire to seek peace.
Chancellor Gorkon was assassinated on the way to the talks by conspirators from both sides, including the Klingon General Chang, Starfleet Admiral Cartwright, the Romulan Ambassador Nanclus and the Vulcan Lieutenant Valeris. Kirk and McCoy were convicted of the murder and sent to Rura Penthe. After escaping, they joined the Enterprise-A in uncovering the plot, and with the Excelsior they destroyed Chang's cloaked Bird-of-Prey and stopped an attempt on the life of the Federation President at Khitomer.
Gorkon's daughter Azetbur, the new chancellor, completed the peace. The accords became the foundation of Federation-Klingon relations for the next century. Gowron withdrew the Empire from them in 2372 during the invasion of Cardassia, but they were restored when the Klingons rejoined the alliance against the Dominion.