The Klingon Civil War was a conflict fought in early 2368 over the right to choose the next Chancellor of the Klingon High Council and de facto leader of the Klingon Empire. The war was fought between forces loyal to Gowron, the legally appointed candidate, and the supporters of the House of Duras, led by Lursa and B'Etor. The war was a decisive victory for Gowron, but it was achieved only through indirect assistance from the United Federation of Planets in exposing covert Romulan assistance to the forces of the Duras family.
The conflict had its roots in the reign of K'mpec, the longest-lived chancellor of the Empire. Although K'mpec ruled with an iron fist and managed to keep peace within the Empire, his influence began to wane as he grew older, and two opposing factions began to develop. The first faction, led by Gowron, favored the continuing alliance with the Federation, while the second faction, led by Duras, sought to establish a more independent and aggressive policy for the Empire. Duras had support from a large majority of the High Council, while Gowron's support came largely from political outsiders and military personnel.
Tensions came to a head in early 2367 with the sudden revelation that K'mpec was dying. He had been slowly poisoned by Veridium Six that had been introduced into his bloodwine. Because the killer had not shown his face to his victim, Klingon tradition considered the act to be without honor. Recognizing the corruption that had taken hold in the Empire, K'mpec decided that he could not trust any Klingon with the task of choosing the next leader of the Empire. Therefore, he took the unheard-of action of selecting Jean-Luc Picard, a Human Starfleet officer, as the Arbiter of Succession.