Praxis Explosion and the Khitomer Accords

In 2293 Praxis, the moon that served as the Klingon Empire's main energy production facility, exploded. The disaster poisoned the atmosphere of the homeworld Qo'noS, leaving the Klingons roughly fifty years before it became uninhabitable, and the Empire could no longer afford its long arms race with the Federation. Chancellor Gorkon reached out for peace, and Starfleet sent Captain Kirk and the Enterprise to escort him to talks on Earth.

Opponents of détente on both sides conspired to derail the process. Gorkon was assassinated aboard his own ship in an attack made to look as if it came from the Enterprise, and Kirk and McCoy were convicted and sent to the penal colony of Rura Penthe. Spock exposed the plot, which involved General Chang, his own protégée Valeris and senior Starfleet and Romulan officials.

With help from Captain Sulu's Excelsior, the Enterprise destroyed Chang's cloaked Bird-of-Prey and foiled a final assassination attempt at the peace conference on Khitomer. Gorkon's daughter Azetbur carried on his work, and the resulting Khitomer Accords opened an era of Federation-Klingon peace.