Raid on Lachesis

The Raid on Lachesis was a campaign conducted by the Graven Star of the Word Bearers chaos space marine legion, alongside Night Lords of the Thirteenth Talon, and Red Corsair mercenaries. Opposing the forces of chaos were the Cobalt Scions, 31st Nightfall Ranger Regiment, and Battlegroup 86. The ultimate chaos aim was the destruction of a Lachesian moon, and through a psychic ritual the use of the remains to construct a warp portal between Eridani and the Eye of Terror. While the forces of chaos ultimately failed and were driven from the world completely, they did succeed in destroying Lachesis Prime's ability to process its vast psychic tithe intakes resulting in a swathe of rogue psyker outbreaks across the system and beyond, and limiting the system's ability to process its psychic intakes in the medium term as temporary facilities were constructed and almost immediately overstretched.

The Raid on Lachesis was a resounding Imperial victory that greatly delayed the arrival of the Graven Star armada, but not without cost. The system remained vulnerable for some time afterwards as rogue psykers were hunted down, and the chaos cults that sprung up from the presence of the Word Bearers were eliminated by Inquisitorial agents.