The Dread Host answered only to the Dread Masters, opposing both the Republic and Sith Empire. It was composed of individuals recruited or mentally enslaved into service from both groups, but was organized along the lines of the Imperial Military. Many soldiers retained their Imperial gear and uniforms, especially when deployed to Section X. When encountered on Oricon the uniforms had changed, favoring red instead of black. The Dread Host commander Malora Pradon who an Imperial officer's uniform shaded in red, rather than gray. It was primarily a ground force, with no known space combat encounters.
The Dread Host included large numbers of Sith combatants, integrated into the units alongside troopers. On Oricon units also included battle droids. The precise rank structure of the Dread Host is unknown, but soldiers and Sith were both found in command roles. The Dread Masters were the unquestioned high command.
The Dread Host was formed during the renewed Galactic War, following the freeing of the Dread Masters from imprisonment. This military unit broke free of the Imperial Military following the presumed death of the Sith Emperor, which freed the Dread Masters from his control.
The precise origins of the Dread Host were not known to the Republic. The unit included Imperial troops and Sith that had served them prior to capture, Imperials defecting to their service, and individuals converted to their forces through their powers of fear and madness. Jedi research indicated that the later group was the largest, with only a few willingly serving the Dread Masters. Attempts to heal the damage done to captured members of the Host failed entirely as they had suffered immensely under the constant psychological manipulations of their masters. The result of this brainwashing had left the Host members not only completely loyal but also paranoid and incurably insane.
A portion of the Dread Host was sent to Asation in the Gree Enclave with the intent of summoning the being known as the Terror From Beyond. This unit was commanded by the reconstructed Trandoshan Warlord Kephess. These forces successfully overcame and corrupted the Gree defenses and began to open the hypergate. However, the Gree requested aid from the Republic and Sith Empire and a strike team was dispatched to the planet. The Dread Host forces stationed there, including commanders Ciphas, Heirad, and Kel'sara, were killed. Despite this defeat the Jedi Order believed the unit had successfully transmitted some information off-planet, including hypergate technology.
The Dread Host was dispatched to Section X on Belsavis in order to secure Rakata artifacts and other technology located in the vaults there. Of principle interest were the Aurora Cannon weapon and the wreckage of the Fatality a vessel they had caused to crash there years earlier and containing a cargo of HK-51 assassin droids. This effort was opposed by both Republic and Imperial forces. The Aurora Cannon was destroyed by a strike team and the Dread Guard Commander guarding it was slain. A spacer recovered the necessary HK-series components to reactivate an HK-51 droid and took possession of the Fatality after killing a Dread Host Sith known as the Lord of Agony.
Dread Master Styrak took a portion of the Dread Host with him to Darvannis during his mission to recruit mercenary and Hutt Cartel forces to his cause. This unit attempted to defeat the strike team sent to disrupt the mission, but was destroyed along with their master.
Significant portions of the Dread Host were stationed on Oricon, surrounding the Dread Fortress, the apparent base of operations for the Dread Masters. These units defended the fortress against attacks by the Republic's Strike Team Oricon and the Empire's Dread Executioners. The Dread Host's numbers were supplemented by Corruptor droids, produced by the Bothrium Beast, corrupted lifeforms, and many corrupted and insane Imperial and Republic troops and Force-sensitives.
Initially able to drive back the attackers to their camps and, with the assistance of the Dread Master's fear induction almost overrun them, the Dread Host was turned back after the arrival of enemy reinforcements and the formation of a temporary alliance between Republic and Imperial forces. The Dread Host was subsequently decimated by enemy action. The Bothrium Beast was slain and the terraforming project destroyed. A spacer infiltrated the central watchtower and seized the control computer located there, killing Commander Zaoron when he attempted to defend it.
The Dread Masters then ordered ships launched to carry a plague of terror to hundreds of worlds across the galaxy, but a strike team penetrated the outer perimeter of the Dread Fortress, destroyed the transports, and killed the commanders guarding them. Shortly thereafter another strike team, possibly even the same one, penetrated the Dread Fortress, killing Dread Master Brontes and locating the portal to the Dread Fortress. There the Dread Masters were slain by the strike team. This resulted in the dissolution of the Dread Host.
The Dread Masters are initially released as a result of player actions in Star Wars: The Old Republic at the conclusion of the Imperial quest line on the planet Belsavis. A considerable portion of endgame content produced since the initial release of the game covers the subsequent actions of the Dread Masters. The Dread Host usually appears in the role of general mobs in quest areas where the Dread Masters are active, and during operations featuring the plans and schemes of the Dread Masters. With the release of Operation: The Dread Palace and the in-game death of the Dread Masters the role of the Dread Host may be considered concluded.
A developer blog provides in-universe entry on this organization.