The Fabricator-General of Mars is the secular political leader of the Adeptus Mechanicus and the Magos Mechanicus or High Priest of the Cult Mechanicus. As the leader of one of the most powerful organisations within the hierarchy of the Imperium of Man, the Fabricator-General maintains a permanent seat on the Imperium's ruling Senatorum Imperialis as one of its reigning High Lords of Terra. "Fabricator-General" is also the title given to the senior Magos who holds sway over an individual Forge World of the Mechanicus by dint of their superior knowledge and insight into their chosen field.
For thousands of standard years the planet of Mars has been ruled by the strange and mysterious caste of Tech-priests known as the Mechanicum of the Cult Mechanicus, who formed a technocratic parliament of theocratic, feudal overlords. This religious sect rose to dominance on Mars during the early centuries of the Age of Strife, and through the Machine Cult, Mars evolved a strong culture and ordered civilisation based around the worship of their "Machine God" or Omnissiah. To the Priesthood of Mars, science and technology were matters of sacred mysteries and arcane religion; matters not only of reason and experiment but of vital ritual and ceremony.
Treaty of Mars
In the late 30th Millennium, after the Emperor unified Terra during the Unification Wars, He launched the Great Crusade into the stars, in order to unite all of humanity under one banner following the Long Night of the Age of Strife, and end inter-human conflict. Sensing a kindred spirit, the lords of Mars recognised the Emperor as a man of science who valued the machine and technological advancement. The Emperor was aware of their scrutiny, having watched the Red Planet from afar and made His plans accordingly. Mindful of this diplomatic opening the Mechanicum's beliefs afforded, and the vast strategic difficulties and destruction to his own forces any (and by no means certain) attempt to take Mars by force would entail, the Emperor sought a negotiated alliance with the Mechanicum Parliament. The Emperor promised to protect the Tech-priests, allow them to continue to practice their religion in contravention of the atheistic Imperial Truth and respect the sovereignty of their Forge Worlds across the galaxy. In return, the Mechanicum would supply materials for His Imperial armies and build a mighty war fleet for His crusade to the stars. This afforded the Mechanicum a level of independence unequalled within the burgeoning Imperium. The Emperor also agreed to supply the Mechanicum with six Houses of Navigators to replace their long dead thrall-Navigators, so that their voidships might once again safely travel through the Warp. Given such an incentive, Mars assented to an alliance, although not without some bloody internal strife over the matter, and the alliance was sealed when the Mechanicum's Ambassador to Terra -- the powerful Fabricator-General who spoke for the Martian Parliament -- was respectfully given a seat on the War Council of the Great Crusade.
The terms of this alliance were then formalised in a binding agreement called the Treaty of Mars (known as the Treaty of Olympus Mons to the Tech-priests after the place on the Red Planet where the Emperor had first trod their soil). This treaty would inextricably bind together the Imperium and the Cult Mechanicus for the next ten standard millennia. To symbolise the alliance created between Terra and Mars that marked the true birth of the new Imperium, the Emperor changed his personal sigil from one consisting of crossed lightning bolts and a single raptor's head, to the Aquila, a two-headed eagle whose heads represented the twin foundations of the new human interstellar government -- Terra and Mars, Imperium and Mechanicum. With Mars now a part of the Imperium, the Great Crusade could begin in earnest and the rest of the Solar System was the first region of space to be conquered by the Emperor and His newly rearmed and re-equipped Space Marine Legions.
Schism of Mars
Though the Mechanicum now served the Imperium, there were many amongst their number who were full of discontent at the new order. The Emperor had imposed an exigence of His own upon the Mechanicum. Well aware of the sad story of the Men of Iron and the inherent danger and vulnerability of certain technologies to the corrupting influence of Chaos, He forbade the Mechanicum to pursue certain types of knowledge, foremost amongst those the development or study of Silica Animus; machines that possessed full self-awareness and were totally independent of human control. The Emperor listed a number of machines and technological concepts that could lead to the combination of technology with the sorcery of Chaos, and ordered those subjects to be considered taboo, and not to be researched by the Tech-priests under pain of execution. Since many such forbidden technologies already existed in various Magi's forge cities or lay hidden beneath the sands of Mars, the Emperor ordered the Fabricator-General Kelbor-Hal to seal all such devices within a special cache that only He or His trusted representatives could open, known as the Vaults of Moravec. The Mechanicum grudgingly acquiesced to this arrangement, but the restraint on the Tech-priests' search for knowledge, even dangerous knowledge, would create resentments that would later reemerge during the Horus Heresy over 200 standard years later.
At the outset of the Horus Heresy in 005.M31, the Chaos-corrupted Warmaster Horus sent Regulus, a Mechanicum representative who had already thrown in his lot with the Warmaster, to Mars to secure the tentative support of the Fabricator-General of the Mechanicum, Kelbor-Hal. Kelbor-Hal was once a brilliant Magos of the Mechanicum and a deep believer in the doctrines of the Omnissiah. The fact that such an ambitious and duplicitous individual ever rose to prominence and the eventual leadership of the Mechanicum is one of the great tragedies of Imperial history. It is remarkable to Imperial scholars of today that an individual as extraordinarily gifted as Kelbor-Hal could be so wrong-headed as to bring so mighty and august a body as the Mechanicum over to the service of heresy and rebellion. When the Emperor had first come to the Red Planet, the masses of Mars believed that the Emperor was the Omnissiah, the physical avatar of the Machine God, a golden figure that trod their planet's red surface. But to Kelbor-Hal and those of his ilk, they believed the Emperor to be a False God who had enslaved the Martian Priesthood to His will with lies. This bitter resentment, harboured over the next two centuries, would fester below the surface, until such time when this rancorous hatred would boil over into a terrible rebellion against the authority of this False God. Playing upon the Fabricator-General's resentment and bitterness, Regulus convinced Kelbor-Hal of Horus' resolve to support increased autonomy for the Mechanicum against the autocratic rule of the Emperor. As a show of his appreciation for the Fabricator-General's support, Horus provided information to the Fabricator-General that would allow the Tech-priests to open the Vaults of Moravec, the repository of forbidden knowledge sealed by order of the Emperor nearly two centuries earlier.
When this repository was reopened, there was all manner of forbidden arcane knowledge and weaponry that had obviously been tainted by the corrupting influence of Chaos stored within. Soon the corruption spread throughout the forges and temples to the Machine God across the Red Planet as scrap code -- Chaos-contaminated digital source code that was infected with an arcane computer virus -- infested the logi-stacks and Cogitator (computer) archives of the Mechanicum, causing literal Chaos to emerge in any Cogitator system that was networked to one of its infected counterparts. Soon the various factions fought one another in open warfare, known as the Schism of Mars, as each side declared themselves for the Traitors' or Loyalists' cause. Following seven Terran years of civil war and untold bloodshed, the Horus Heresy ended in a pyrrhic victory for the Imperium. The traitorous Forces of Chaos that had served Horus were driven towards the Eye of Terror during the brutal military campaigns remembered as the Great Scouring. The Renegade Tech-priests of the Dark Mechanicus were also driven from Mars by the resurgent Loyalists amongst the Mechanicum. These Renegades fled the Imperium into the far corners of the galaxy and some also took refuge within the hellish realms of the Eye. In exile, the Dark Mechanicus became even more enthralled to the power of the Warp and heretical technologies. The ultimate fate of the traitorous Fabricator-General Kelbor-Hal is currently unknown.
- Kelbor-Hal - Kelbor-Hal was the Fabricator-General of Mars during the latter days of the Great Crusade and the Horus Heresy in the early 31st Millennium. When the Heresy began he swore allegiance to the service of Warmaster Horus and the Forces of Chaos, becoming the first leader of the Dark Mechanicus. In the name of his new allegiance, Kelbor-Hal would unleash the terrible civil war known as the Schism of Mars upon the Red Planet, the sacred heart of the faith of the Machine God.
- Gastaph Hediatrix - Gastaph Hediatrix was the reigning Fabricator-General during the Age of Apostasy, a second period of civil war in the Imperium of Man during the early 36th Millennium when the Imperium's government was essentially seized by a single man, High Lord Goge Vandire, who ruled the Imperium according to his own wishes instead of in accord with the Emperor's will. Enraged by what he saw, Hedriatix ordered regiments of the Martian Tech-Guard to transport to Terra. These regiments were joined by multiple Space Marine Chapters comprised of the Black Templars, Fire Hawks, Imperial Fists and Soul Drinkers, who assaulted the Ecclesiarchal Palace, the central complex which housed the Apostate High Lord, and ended Vandire's Reign of Blood. The Fabricator-General, with the help of the Space Marine Chapters, set about resurrecting what remained of the High Lords of Terra and played an instrumental role in ensuring those who profited from the Reign of Blood would face trial for their conduct.
- Zagreus Kane - Kane was a Fabricator Locum during the time of the Great Crusade and Horus Heresy. During the opening days of the Schism of Mars he would succeed the traitorous Kelbor-Hal as the new Fabricator General. When First Captain Sigismund and four companies of Imperial Fists landed on Mars to secure the forges munitions, weapons and Power Armour, Kane aided Sigismund by ordering nearly all of his servitors to help load weapons and armour onto awaiting transports to be taken to Terra.
- Codex Imperialis, pg. 41
- Codex: Sisters of Battle (2nd Edition), pp. 13, 15
- Dark Heresy: The Lathe Worlds (RPG), pg. 10
- The Horus Heresy - Book One: Betrayal by Alan Bligh, pp. 17-18
- Warhammer 40,000: Rulebook (6th Edition), pg. 402-403
- Warhammer 40,000: Rulebook (4th Edition), pg. 121
- Mechanicum (Novel) by Graham McNeill