- "By destroying the dreadnought and spreading word that the Dread Masters had been killed, the Council hoped to prevent the Emperor from making any attempt to locate them. The truth was, however, that the Council believed the Dread Master were far too valuable to dispose of."
- ―Grand Master Satele Shan
In 3668 BBY during the Great Galactic War between the Galactic Republic and the Sith Empire, members of the Jedi Order and Republic Special Forces Division organized a mission to stop the Dread Masters—a group of six ancient Sith Lords who were terrorizing Republic naval fleets through use of the dark side of the Force. The Dread Masters' power in Sith magic allowed them to remotely and anonymously induce crippling fear in enemy vessels, sending their crews fleeing in panic and seriously damaging the Republic war effort. Despite efforts to keep the six of them hidden aboard a Harrower-class dreadnought, Imperial communications regarding their identity and location was intercepted by the Republic Strategic Information Service, allowing Jedi Knight Jaric Kaedan and a Republic Special Forces team to plan a strike against the Dread Masters. The operation was successful and ended with the capture of the Sith Lords and the Republic's acquisition of a highly-classified Imperial database. Although their dreadnaught was destroyed, the Masters were kept alive and ferried to The Tomb, a maximum security section of the Republic's secret prison on Belsavis in the Outer Rim Territories.
- "In a string of recent confrontations with the Empire, dozens of Republic warships had gone missing, leaving evidence that they fled after personnel on board were overcome by a profound and mysterious terror."
- ―Jedi Master Gnost-Dural
- "Working with an elite Republic Special Forces team, Jedi Knight Jaric Kaedan managed to infiltrate the dreadnought and capture the Dread Masters."
- "The ancient prison on Belsavis was the only place with safety measures strong enough to ensure the Dread Masters could not escape, and it is there they remain to this day. Let us hope that they remain there for all eternity."
- ―Satele Shan
- Star Wars: The Old Republic (Mentioned only)
- Star Wars: The Old Republic: Rise of the Hutt Cartel (Mentioned only) (Codex entry)
- The Journal of Master Gnost-Dural (First mentioned)