Klingon Civil War
The Duras faction attacked immediately, only narrowly missing their chance to assassinate Gowron in the opening battle of the war. Birds of Prey loyal to the Duras faction attacked Gowron's flagship in orbit above Quo'nos and would have destroyed it if not driven off by a squadron lead by Worf's brother, Kurn.
The war continued for an unspecified period of time, with rebel forces seeming to get supplies and repairs from nowhere, forcing Gowron to defend his position in at least one duel.
The Federation suspected that the Duras family was receiving supplies from the Romulans, so they deployed a fleet to blockade the Klingon-Romulan border with a tachyon net. Romulan supply ships attempted to run the blockade, but their trick was exposed by Commander Data, forcing them to retreat and leaving the Duras forces on their own. Cut off from Romulan support, the rebel faction was soon defeated.