A mission was undertook by the New Republic in the Spawn Nebula during the Galactic Civil War to investigate ans eliminate the Kaarenth Dissension in the Corva sector.
Not long after the end of the Thrawn campaign, a group of New Republic was dispatched to investigate the increased presence of the Kaarenth Dissension in the Corva sector. On the planet Betha II, the operatives identified Meres Ulcane as the leader of the Kaarenth Dissension in the sector.
Using the experimental Drooim-Durtha Systems ShipFinder device, the New Republic operatives were able to successfully track Ulcane's vessel from Betha II to his secret base, hidden in the Spawn Nebula. The Kaarenth Dissension base was in fact a huge worldcraft repurposed into a repair facility and shipyard hub. Moreover, the New Republic operatives discovered that the worldcraft was orbited by an entire fleet of warships, including assault shuttles, system patrol crafts, frigates, Strike-class medium cruisers and one Imperial-class Star Destroyer. This secret fleet, currently without crew, had been assembled over the year to strike one day the New Republic. Following a freighter that was heading to the space station, they were able to land their ship, the Instigator, in one of the sphere's hangars. The New Republic agents successfully infiltrated the worldcraft and even managed to access the main reactor section where they planted explosives, namely illerium. However, the operatives were finally spotted and attacked by stormtroopers. They hastily rushed to the hangar and departed in their starship. Once in space, they were attacked by eight TIE fighters but the Instigator destroyed them all. An Interdictor cruiser later arrived in the area but it was too late to prevent the New Republic ship to enter hyperspace. The explosives planted in the worldcraft detonated at this very moment. The explosion destroyed the giant sphere and the shock wave wiped out the starships nearby.
The destruction of the Kaarenth Dissension fleet in the Spawn Nebula ruined definitively the chances of the Imperial faction to overthrow the New Republic in the Corva sector. The death of Meres Ulcane and the loss of most of his fleet was a severe setback for the Dissension but the use of illerium to destroy the worldcraft eventually inspired Ennix Devian, the leader of the Kaarenth Dissension, his next attack against the New Republic.
- The Complete Star Wars Encyclopedia