Thys is world contested by the native colonists and the Terran Dominion. The colonists are known to be anti-Dominion, and the Dominion sought to have them removed. The planet has vast vespene gas reserves.
Thys was populated by terran colonists who came seeing the vespene gas reserves on the planet. The managers of the mining operation were very anti-Dominion, and Colonel Garr considered them to be traitors.
Later, Thys was attacked by a massive wave of zerg forces. The Terran Dominion sent forces to interveene, and Colonel Gar deployed the Lost Wolves and the Tamed, a squadron of pacified hydralisks. They cleared through the zerg, but Colonel Garr gathered all of the colonist's councilors and ordered Dr. Sandra Loew to turn the Tamed on the vespene mine and kill any resisting colonist. Loew instead turned the Tamed on Garr and his forces, killing Garr, his security, and the colony's councilors.
Loew then attempted to kill off the Tamed using somnus, but the Tamed revealed themselves to have only been pretending to be pacified by the Dominion. They killed off the Lost Wolves, and then the hydralisk Loew had formed a personal attachment to, Dennis, turned on Loew and killed her.