Mezoa - The Blockade of Mezoa: Shortly after the denial of Regulus, a blockade of Mezoa was begun. With the help of the warships of M'Pandex -- both their own Mechanicum vessels and those they had since captured and now operated under a false flag, as well as more shadowed forces operating under Horus' direction -- the various star systems that fed into Mezoa were cut off from it, with the aim of choking off its supply of raw materials. Resources which, where possible, were now directed instead to the hungry forges of M'Pandex.The Mechanicum on Mezoa actively resisted where they could, although they steadfastly refused to sally forth with their full force, treating the attacks as bait in a trap. Instead, they ordered their outposts and detached forces to resist until destroyed, and on far-flung mining stations and on the decks of mass transporter vessels, the forces of the two Forge Worlds, long rivals but never before enemies, clashed in mortal combat.Mercy was not to be found in either sides' circuit-augmented hearts, and the Adsecularis cohorts of M'Pandex were matched savagely by the armoured centuries of Mezoa's Thallaxii which, while fewer in number, vastly outmatched the Adsecularis in individual might. In what seemed now to outsiders to be a civil conflict within the Mechanicum rather than a move in a wider game, refinery stations on Jujya and Gunnar's Rock burned, and on New Providence, thousands of fleeing vapour-mill workers caught between the battle lines, were crushed beneath the tracks of Krios tanks and slaughtered needlessly in the withering crossfire of blazing energy weapons as both sides utterly ignored them.By the end of 007.M31, the Mezoan System had been almost entirely cut off from the wider Imperium, and now enemy warships were circling the edge of its outer reaches as sharks waiting for prey. Mezoa was a prize not to be underestimated, but it was also fortified beyond ready conquest, even by a force as large as a fully marshalled Expeditionary Fleet. However, once cut off from aid and from giving aid to others, it was now effectively neutralised. As other star systems declared for Horus, the blockade was increasingly reinforced, most decisively after the Fall of Port Maw which saw the blockading fleet reinforced by turncoat siege-monitors of the Armada Imperialis, the pale-hulled Legion warships of the Death Guard Legion, as well as dark-hulled vessels of unknown provenance that now bolstered the Traitors' forces.Eventually the force amassed was sufficient to mount an attack on the beleaguered Forge World. This first great assault would be hurled back under mysterious circumstances, the Mezoan Magi having somehow succeeded in turning the very fabric of their molten world against their attackers, causing vast swathes of the planet's mantle to suddenly and violently collapse under the enemy's landing zones. The wilder reports even told of colossal island-size chunks of magma hurled up into space and flung at the attacking ships.Regardless of the truth, that the Traitor forces had been hurled back was known, but Mezoa was but a light in a sea of night, and how long it would last could not be predicted. The initial blockade would become a full-fledged siege, marking the beginning of the Siege of Mezoa which would continue for the better part of the Horus Heresy. The Siege of Mezoa would mark one of the few confirmed appearances of Traitor elements drawn from the remains of the three Loyalist Legions massacred at Istvaan V, the Forge World's siege seemingly having mobilised a company-size element of Blackshields wielding both the weapons of the Iron Hands and the Sons of Horus.