Discerpo Campaign

The Discerpo Campaign was a campaign of retribution launched by the Castigators Chapter against the Forces of Chaos upon the Imperial world of Valst, but ultimately the Imperial forces would be forced to make a fighting withdrawal and launch Exterminatus upon the doomed Chaos-held planet so the Ruinous Powers could not claim it as their own.

History
When the world of Valst was attacked by a massive host of the Forces of Chaos, the Castigators Chapter were called upon for aid. In response they sent their 2nd Company to assist. When they arrived at the beleaguered planet, the 2nd Company penetrated the planetary surface of Valst, near the city of Nisandria. Here, they destroyed multiple defence batteries, allowing three regiments of the Astra Militarum and two Titan Legions to assault the city. But ultimately, the Discerpo Campaign would end in abject failure, leading to a fighting retreat, as the Ruinous Powers claimed the doomed planet for their own. The Inquisition ordered an Exterminatus upon the lost world, and declared it Perditas.