Klingon Civil War

The Klingon Civil War was an internecine conflict fought within the Klingon Empire in late 2367 and early 2368. The war was waged between the supporters of the House of Duras and of Gowron, over who would be the rightful successor to K'mpec as Chancellor of the Klingon High Council. The forces backing Gowron were ultimately victorious, after it was revealed that the House of Duras was receiving backing and material support from the Romulan Star Empire. (TNG episodes: "Redemption, Part I", "Redemption, Part II"