Cleansing of Lutum VI

The Cleansing of Lutrum VI was an Imperial xenocidal purgation campaign carried out by the 501st Cordanian PIR alongside various military forces of the Imperium on the mining world of Lutum VI, which had fallen under the control of an insidious cult of vile Genestealers.

History
Within the Quisquiliae sub-sector, a mining world of Lutum VI went into revolt when the planetary governor declared that planet was no longer under Imperial control. Communications were shortly cut off after the revolt. The Departmento Munitorum and Segmentum Command ordered the 501st, 182nd and the 101st Cordanian Regiments to meet up with Inquisitors representing both the Ordo Hereticus (Inquisitor Veruim Orruptem) and the Ordo Xenos (Inquisitor Noli Timere). Much of the disgust to the General Officers in aiding the Inquisition, they followed their orders and continued their duties to the Imperium.

When the Imperial fleet entered the system, they were shot at from Lutrum's surface, but they managed to make contact with the surviving Lutum PDF. They were then informed as to why the revolt had occurred - the planetary governor was, in fact, part of an insidious Genestealer Cult. This situation also did not help that most of the population had fallen under the control of these vile xenos infiltrators. Receiving such grave news, the Inquisitors knew that this was just the first stage of an inevitable Tyranid invasion, and if they did not get back control of the planet before the hive fleet arrived, the surviving population would be consumed by the Great Devourer. Or in the worst case scenario, the Inquisition would be forced to enact Exterminatus upon the doomed world in order to deny the Hive Fleet of biomass. The Imperial force knew that had to act fast if they wished to save the planet and its people from damnation.

The Imperials quickly managed to retake control of the planetary defense weapons of Lutum's main military base, then called in for more support. Within 8 weeks, they managed to receive a full Astra Militarum Shock Troops regiment from Cadia and several companies from both the Raptors and Iron Hands Space Marine Chapters. The Imperial forces on Lutum even received several companies from the elite xenos-hunting Deathwatch Space Marine Chapter. But what surprised them most, was when they received aid from a Commandery of the Order of the Argent Shroud of the Adepta Sororitas, that was enroute back to their homeworld when they received the astropathic distress message. Commanded by Canoness Commander Maria, the Battle-Sisters quickly changed course and went to aid the Imperium's efforts to cleanse the planet from the Genestealers after receiving the call for aid. It took three years to fully cleanse the Genestealer cults off the planet - city by city, settlement by settlement, mine by mine and one sewer at a time.

By the end, most the main population of 50 million had been whittled down, with at least 2-8 million citizens left alive and uninfected by the cults. But most of the population was either slaughtered by the cults or had become infected. As there was no known cure for those infected by the Genestealers, the Imperial forces knew they had to kill both the host and their vile offspring. Those who were infected that are willing to die, are granted a painless death, while the ones being uncooperative or violent were summarily executed. The estimated amount of casualties is still pending even after a decade. The amount of Genestealers that were killed, numbering approximately 20-40 million, or perhaps even more. However, even if the planet was cleansed of Genestealers, there is still the lingering threat that a Tyranid hive fleet may still be coming.

Sadly, after the events of the Gathering Storm, the entire Imperium was severely weakened following the formation of the Great Rift. The Tyranid Hive Fleet Therone had come to consume the planet. Only a few ships managed to escape the doom world while the Great Devourer consumed all that failed to escape or those who vainly stood and fought back.