Purging of the Astral Hounds

The Purging of the Astral Hounds was an Imperial excoriation campaign conducted by the Emperor's Reapers Space Marine Chapter against the Astra Hounds Renegade Chapter, which had been declared as traitors by the High Lords of Terra.

Background
In 129.M33, due to unknown reasons, the once-stalwart Astral Hounds betrayed the Imperium and were quickly declared Excommunicate Traitoris by the High Lords of Terra. The vengeful executioners of the Emperor's Reapers Chapter answered the call-to-arms, and immediately set out upon a crusade against the Renegade Chapter to ensure that they would be utterly annihilated and wiped from the Emperor's sight. Over course of five years, the the Emperor's Reapers hunted down and slaughtered the Heretic Astartes and purged the population of the Astra Hounds home world, without hesitation or regret. Even those that professed to still be loyal to the Imperium, it mattered not. They still met a grisly fate at the hands of the Emperor's Reapers' scythes, which earned the Chapter an infamous reputation for being the Imperium's merciless and brutal executioners. The Chapter tore down the Renegade Chapter's fortress-monastery, chattels and infrastructure of their home world, until nothing remained by piles of rubble and mounds of the dead. No one was spared their wrath. This fell reputation led the Emperor's Reapers to begin to be feared by some of the other more level-headed, Codex Chapters of the Adeptus Astartes.