Sigismund - Mission to Mars: In the opening days of the Horus Heresy when the Schism of Mars erupted, open warfare raged across the Red Planet between the forces of the Loyalist Mechanicus and the traitors of the Dark Mechanicus. Malcador the Sigillite, the Regent of Terra, charged the Primarch Rogal Dorn with a mission of vital importance -- to secure the forges of Mars. Dorn informed the Sigillite he would send First Captain Sigismund and four companies of Imperial Fists to carry out the task. The forges of Mondus Occulum and Mondus Gamma produced the bulk of the armour and weapons of the Astartes. He would have them strike there first and when they were in Loyalist hands, the Imperial Fists would push outwards and secure the others.Sigismund's companies landed at Mondus Occulum as the rest of the Imperial expeditionary force was fighting across the surface of Mars. After a rapid deployment under fire in the shadow of Pavonis Mons, thirteen companies of the Saturnine Hoplites regiments of the Imperial Army advanced on the lines of circumvallation surrounding the forge of Ipluvien Maximal. Further south, two companies of Imperial Fists and four regiments of Jovian Grenadiers (nearly 15,000 Imperial Army soldiers) under the command of the Imperial Fists' Captain Camba-Diaz made planetfall in the Mondus Gamma forge complex.Nothing of their mission to Mars panned out the way it was supposed to. Camba-Diaz and the Jovian regiments were embroiled in a fight for their lives at Mondus Gamma, and the Saturnine companies tasked with breaking the siege at Ipluvien Maximal's forge had been repeatedly turned back by the horrifyingly altered weapon-creatures of the Dark Mechanicus. Though the fighting proved desperate, Camba-Diaz secured the armour forges and the ammunition silos, but his company was outnumbered a hundred to one. The Traitor Chrom’s forces pushed him back to the landing fields and his losses were grievous. Sigismund knew the Imperial expeditionary force would not be able to hold the forge, but a great deal of essential supplies had been secured for transit to Terra.Sigismund's companies had descended upon Mondus Occulum not knowing whether they would have to fight to secure the forge, but it was a relief to find that Fabricator Locum Kane still held true to the Emperor. Sigismund secured vast quantities of munitions for shipment back to Terra, including nearly 12,000 suits of Mark IV Power Armour and twice as many weapons. But the Loyalists had run out of time. Despite the locum's Servitors working at full capacity, it still was not fast enough to load the bulk transports, for Sigismund's ship masters informed him of a sizable enemy force closing in, composed of Traitor infantry, armour, Skitarii and at least two Titan Legions comprising nearly 60 war engines in all.Sigismund's desire to wreak a bloody vengeance on those who rebelled against the Emperor warred with the mission his Primarch had given him of securing the armour and weapons of Kane’s forge. Reluctantly he knew he must stay true to his mission, for the forces arrayed against them were too many and his orders did not allow for futile gestures of defiance. Locum Kane warned the Imperial Fists' First Captain that if both the Mondus Occulum and Mondus Gamma forges fell, the Imperium would have no way of replenishing the combat losses they would sustain against the Traitors in any meaningful way.After only a few hours' worth of fighting both Mondus Occulum and Mondus Gamma were burning, and vast swathes of machinery and manufactorum capacity had been destroyed. The loss of such irreplaceable technology and knowledge would be felt by the Imperium for millennia to come. Like comets launching from the surface of Mars, the Imperial transports fled into the heavens. Astartes and Imperial Army vessels jostled in the sky in their haste to depart the crimson world. But the mission was successful and the Loyalist Astartes had secured a large number of the new marks of Power Armour in preparation for the oncoming campaign against Terra by the Traitor Legions of Horus.