The Dark Council is plagued playing the old games, grabbing for power that they don;t deserve. Now the Lords of my Empire see an opportunity to gain new power and position. This is what Tomus feared, this power playing with destroy the Empire. I've rallied the remnants of the Inquisition, now we make our move.
—Exar Kuen talking to Tomar Vaner about the fragmenting Empire.
The Fragmentation Crisis was a series of conflicts both political and military. It was a near secret conflict between the Emperor and the power playing Dark Lords and Sith Lords. Targath Vile'tor used dissidents within the Empire to help fuel is ambition to have the Sith Government rule the Empire. Targath began to use his allies to plant rumors of Lords playing the old games. With the Inquisition distracted, Targath killed a rival Sith Lord and blamed one of his enemies. His enemies power base grew and bold Lords began to plot against each other, the Inquisition was overwhelmed and hunted down its members killed or enslaved.
Targath consolidated his power base and cultivated new allies, power plays within the Sith Order became common place once again. The Dark Council reeling from the lose the Sith Inquisition was unable to stop so many power plays many Sith Lords were successful, further weakening the Emperors position.