Mezoan Campaign - War in the Coronid Deeps: Following the revelation of the Warmaster's true intent in the Istvaan System, the worlds of the Coronid Deeps were the first to suffer from the Traitors' expansive efforts. Led by the Warmaster himself, the Sons of Horus quickly captured the heavily industrialised Manachean Commonwealth in the short-lived Manachean War, whilst their allies in the Death Guard under the command of their own Primarch Mortarion cleansed the strategically less important Grail Abyss of all life. Most importantly, through the events of the Treachery at Port Maw, the Warmaster captured a sizable Armada Imperialis naval fortress and orbital shipyard which would allow him to rearm and repair his fleets during the long march to Terra. By the end of 008.M31 only a few Imperial domains were spared the wrath of the Traitors' armies. To the galactic west, the isolated worlds of the Agathean Domain were deemed too insignificant to squander valuable military resources on conquering it, while in the Cyclops Cluster the Forge World of Mezoa proved a far too difficult target to assail readily. As the Great Crusade had done centuries before, the Traitors' advance would circumvent Mezoa and blockade it until enough men and resources could be gathered to take the strategically important domain of the Mechanicum.While many worlds of these far-flung territories were deemed not valuable enough to offer any kind of coordinated resistance or threat -- which at least in the case of the Agathean Domain would prove to be a gross miscalculation -- the Warmaster knew that he could not ignore the powerful Mezoan Mechanicum. However, having challenged his father for the rule of the entire Imperium of Mankind, Horus, the pretender, could not afford to be delayed in the Coronid Deeps, but had to be seen on the frontlines leading new conquests and rallying new star systems to his banner. The task of eliminating the threat posed by the Loyalist Forge World would be handed down to other military commanders belonging to the Warmaster's allies. Yet such a general could not readily be found. Horus' own puppet-ruler, Taloc Thorne, the Tyrant of Port Maw, lacked the military forces to both maintain productivity in the Manachean Commonwealth and conduct a military campaign of the scale required to conquer the belligerent Forge World. Horus' principal ally in the region, the Dark Mechanicum Forge World of Cyclothrathe, preferred to accomplish its own objectives rather than obey Thorne's orders. In truth, only the Forge World of M'Pandex, a long-time rival of Mezoa, showed any devotion to the Loyalists' eradication. But long eclipsed by its rival, M'Pandex too, lacked the military resources to vanquish Mezoa alone. Two previous attempts to seize Mezoa's principal forge-fane had already been repelled, as the Mezoan Magi used their world's own volcanic might against the invaders, letting the ground collapse under the Traitor's landing zones and rerouting lava-streams to stall any advance or burn their enemies to ashes. Some of the most exotic reports of the earlier campaigns from the survivors even told of kilometer-long chunks of solidified magma, essentially man-made asteroids, that had been flung as projectiles at incoming enemy ships. The kinetic impact alone had been powerful enough to break a voidship in two.