Indomitus Crusade - The Grand Muster: Not since the Warmaster Horus' fleet darkened the heavens above Terra had the Imperium known such a time of crisis as it did in the days following the opening of the Great Rift. Half of the Emperor's realm was gone, vanished behind a veil of nightmares and -- for all those on the Throneworld knew -- annihilated at a stroke.Those worlds in the newly-designated Imperium Sanctus on the Terran side of the Great Rift fared little better. Distress calls, desperate screams, and grim last transmissions all but drowned the minds of Terra's astropaths and drove many mad. There was not a world, it seemed, that was not beset by war.Everywhere the High Lords of Terra turned their gaze the armies and fleets of the Imperium were scattered, besieged, and outnumbered. Untold trillions of Imperial citizens died with every solar day that passed. Worlds winked out like snuffed candle flames from the far reaches of Segmentum Pacificus to the storm-wracked tumult of the Charadon Sector. Time was desperately of the essence.Despite his newfound appointment as Lord Commander of the Imperium, Roboute Guilliman knew that he could not respond immediately. Inquisitorial Vox-thief logs of the Primarch's private conversations during those dark days reveal that Guilliman wrestled with the impulse to draw his blade, rally what warriors were available to him, and take ship for the nearest war zone.In his place many of his lost brothers would perhaps have done just that. But it was both Roboute Guilliman's blessing and curse to see always in terms of the bigger picture. He understood better than any that humanity faced a war not for territory but for survival, that every weapon in the Imperial arsenal must be wielded in concert and with a degree of skill that only he could achieve, and that losing perspective even for a moment might see him win a handful of battles only to lose the wider war for his father's realm.Thus Guilliman took all his rage, all of his hatred of the Traitor foe and his dismay at what had been done to the Imperium, and he channelled it into the mustering of the Indomitus Crusade. He would forge not mere armies, nor even crusades in the traditional Imperial sense, but rather immense fleets of vengeance and reconquest that dwarfed all that had come before them. With these tools at his disposal, Guilliman would fight back against the lackeys of the Dark Gods.He set out his plans to the High Lords with what could best be described as forceful determination, having set a dozen schemes and more in motion before he even secured their agreement. The moment astropathic communication could be re-established with the wider Sol System, the Primarch sent missives winging out to Mars, Titan, Jupiter, and dozens of other worlds and deep-space fortifications besides.He spoke to Archmagos Belisarius Cawl, impressing upon his ancient ally the importance of speed in the undertaking of the Ultima Founding. He secured every space-faring asset he could lay his hands on and began the process of gathering one flotilla after another in deep space beyond Neptune.Guilliman went in person to beseech the Abbess Sanctorum of the Adepta Sororitas and the Fabricator-General of Mars for aid in his undertaking; few know what promises or assurances Guilliman made to these two influential figures, but for whatever unknown price he secured their cooperation.If Terra was to be his fortress and Sol his mustering ground, the Primarch could not afford to risk instability or insurrection endangering his efforts. He made overtures to the Inquisition, the Adeptus Custodes, the Adeptus Arbites, the Ecclesiarchy, and even the Officio Assassinorum to aid him. So began a time of brutal purges throughout Terra's sprawling macro hive cities that saw hundreds of petty cults uprooted and millions of alleged Heretics, mutants, and recidivists burned alive in the streets.Few were safe from this campaign of terror, which soon became known as "The Primarch's Scourge" and saw a shocking number of corrupt officials, dilettante cult-magisters, and self-interested high acolytes culled from Terran high society. Horron Sch'est, the notoriously arrogant and conservative Consul Pre-eminus of the Navigator Houses, was publicly flogged to the widespread shock of all. He had attempted to hold the crusade muster to ransom by withholding the aid of the guilds pending promises of richly preferential treatment from the High Lords, but he soon found that Guilliman's patience for such manoeuvring was nil.Within solar weeks of the ratification of Guilliman's plans by the High Lords, several all-out wars were raging through the Terran underhives as xenofile cults and Chaos worshippers fought desperately for their survival. Collateral damage spiralled. Voices of dissent murmured wherever they did not believe they could be heard. Yet as a result of the scourge the Primarch's muster went uninterrupted by sabotage, sedition, or politicking -- at least in the main.For Guilliman himself, the most troubling aspect of the muster was the process of triage he was required to enact throughout the Segmentum Solar. The entire principle of the Indomitus Crusade required the amassing of immense military forces in and around the Sol System and its neighbouring star clusters; by this point, the Primarch had expressed a desire to gather as many as ten such almighty assemblages.These fleets would muster one by one as sufficient forces became available before striking out on predetermined routes across the Emperor's realm. A great part of the materiel and manpower required for the Indomitus Crusade was slated to come from Mars in the form of both the Ultima Founding Primaris Space Marines and the red planet's own vast strength of Skitarii, Knight and Titan maniples, Ordinatus war engines, and the like.More would be drawn from the Order of the Ebon Chalice and, to a lesser extent, the Order of Our Martyred Lady, from the ranks of the Adeptus Custodes and the Inquisition, and from the mighty warships of the magnificent Battlefleet Solar. However, substantial martial strength was also to be drawn from the systems within Terra’s wider orbit, and it was these embattled realms that Guilliman was forced to assess with a cold and logical eye.Some worlds, it was clear, stood a fighting chance of survival on their own account; where reports spoke of determined warriors and blade-swift warships holding the line, of xenos and Heretic foes being pushed back and held at bay, there the Primarch allowed the armies of the Imperium to fight on.For every star system that was fighting back against the encroaching darkness, however, there were many more whose defenders were on the verge of being overwhelmed and would never hold out without aid. It was these forces that Guilliman ordered to retreat, often leaving just enough of a rearguard behind to ensure that their withdrawal could be achieved without substantial further losses. Thousands of regiments of Astra Militarum and battle-damaged Imperial Navy warships fled from war zones that they had bled and suffered to protect.Some refused their orders, fighting to the last against the terrors that beset their worlds. Guilliman could speak no word of censure against them. Yet equally he did not relent, for he understood as they could not how vital these recalled forces would be to the Indomitus Crusade as a whole.Worlds could be retaken. Territory could be reclaimed and repopulated as the crusade fleets drove outward into the stars, but to squander the Imperium's armies in the hopeless defence of too many battlefronts at once would achieve little but to see the Emperor's realm bled to death.So Guilliman asserted. So he told himself time and again as wounded and resentful armies wended their way back to the Sol System and outlying systems were overrun in their wake. It was a tragedy, but a necessary one. All would be paid back in blood when the Indomitus Crusade began.