Malachai IV Massacre

The Malachai IV Massacre is an infamous Imperial purgation campaign carried out by the ferocious and unforgiving Sable Lions Space Marine Chapter upon the recalcitrant world of Malachai IV. The Sable Lions are censured by the High Twelve for the massacre they instituted against wide swathes of the planet's population - an action for which they remain unrepentant - and were forced to undergo a Penitent Crusade for their actions.

History
The Sable Lions conduct a ten year campaign on the hive world of Malachai IV, to eradicate rebellious factions and those believed responsible for the uprising -- Chaos-corrupted Imperial officials. The Sable Lions are censured by the High Lords of Terra for the widespread culling of the population that marked the end of the campaign and leaves the world unable to fulfil production quotas owed to the Administratum. Unremorseful, the Sable Lions voluntarily undertake a fifty year penitent crusade as recompense.