"We are all but a weapon in the right hand of the Emperor."
- — Exhortations Principiis Titannorum, Diviso Militaris
The Taghmata Omnissiah (translated from Lingua-technis into the Terran Gothic of the Imperial Court as, "That which is divinely ordered for war") was the principal type of operational military force of the trans-Martian Mechanicum and also the most numerous at the time of the outbreak of the Horus Heresy during the opening years of the 31st Millennium. To those outside the arcane secrets and strange mysteries of the Mechanicum, the Taghmata was a difficult thing to grasp, seeming at once a purely descriptive term applied to a bewildering tapestry of Magi, machineworks and indentured manpower, and also a rigid and labyrinthine hierarchical structure, the equal of any in the Imperium's armed forces in complexity. This organisation was the military reflection of a Forge World's essentially feudal power structure mustered for battle. Alongside the elite Skitarii regiments, whose allegiance and command was owed ultimately to Mars, and the Collegia Titanica which comprised the planet-shattering Titan Legions, both of which operated separate military traditions of their own, the Taghmata formed the great trinity, the "Triad-Magna," of the Mechanicum's power during the Great Crusade. Besides these three there stood the "lesser" independent and allied divisions of the Mechanicum such as the Knight Houses, the Ordo Reductor, the Explorators and the Legio Cybernetica, among others. Each was a great power in its own right, but all were dwarfed both in scale and reach by the great three.
Although Mars itself was a highly singular and unique entity in military terms, much as Terra itself was to the other worlds of the Imperium, each Forge World in the days of the Great Crusade was an independent power; a kingdom in its own right. While each owed fealty to the Lords of the Red Planet, in some cases these bonds were as absolute as satrapies, while in others the ties to the Mechanicum's seat of power were weaker, often simply through distance, and in the most extreme cases this fealty became questionable at best, and rivalry and the threat of rebellion against central control or internecine conflict distinctly possible. By this web of fealty, bound more by common religious doctrine, culture and mutually-shared obsession rather than by principle, loyalty or duty was the shadow empire within the Imperium that was the Mechanicum before the Horus Heresy formed.
The proof of this hidden disunity was given unequivocal form during the Horus Heresy when, just as the Imperium was riven by the treachery of the Warmaster Horus, so was the Mechanicum, already rife with internal discord and disharmony, all too readily riven alongside it, turning on itself as well as siding unequally for the warring parties of Traitor or Loyalist, with Forge Worlds and domains siding along long-held fealties and feudal obligations as much as they did for Emperor or the Warmaster. It was of this complex feudal structure, both on the macro-scale which encompassed whole Forge Worlds and alliances of Forge Worlds, and on the local scale of orders, colleges, fanes and forge cities, that the Taghmata system was a direct reflection.
During the cataclysm of the Horus Heresy, the Taghmata was called upon on every Forge World and outpost as war and the threat of attack was constant. Soon, the Mechanicum was engaged in a battle for survival both against outside enemies and against rival factions of their own kind, and what had been an organisation of defence became just as frequently a means of attack, whether to claim vital resources, expand a sphere of influence or simply to annihilate an enemy. As the bloody struggle worsened, many Forge Worlds fought to the death to preserve their sovereignty from invasion by former allies, while others took an active and aggressive hand in the unfolding galactic civil war, their Taghmata fighting alongside Loyalist or Traitor, or simply for their own ends. So it was that Mechanicum slew Mechanicum, Mechanicum slew Legiones Astartes and Legiones Astartes slew Mechanicum. In desperate battle were dark sciences and ancient secrets better left undisturbed turned to, either in vain hope of ensuring survival, or by wakened ambition and lust for power, and the nightmarish terrors of the Age of Strife were unleashed once more.
The Structure of the Taghmata
Each Forge World of this age was itself a patchwork web of complex loyalties, made up of independent and semi-independent domains, both in terms of physical infrastructure and territory and, perhaps more importantly, of knowledge, craft and sacred rite. So it was that each Forge World was not merely a powerhouse of industrial production vital to the wider Imperium which it provided for, but also an empire of secrets unto itself. While nomenclature and structure was hardly uniform between them, the masters of these empires were its Magos and Archmagos -- its "Learned Ones" -- each were lords both temporal and spiritual whose power was that of life and death in their own domains.
Each specialised in a particular facet of the Machine Cult's lore or commanded a sizable measure of their world's infrastructure as their portion, and by this right took their place in the synod that provided the Forge World with its governance and control. Each Magos commanded their own resources and military might, armies of retainers and cohorts of war machines outfitted and formed by their master's will and in accordance with their master's specialisation and proclivity. These were the Taghma, the building blocks from which the Taghmata were formed. When a Forge World's master, the Fabricator Archmagos-Intendant or Archmagos Archimandrite under whose rule the synod served, called a Taghmata into being, it was the sworn duty of each Magos to provide such troops and assets as was demanded of them, and through them such lesser Tech-priests and Adepts, sub-cults and esoteric orders who owed fealty and vassalage to the High Magos were called on, and so on throughout the patterns of seniority and allegiance that crisscrossed the Forge World.
In many cases such calls to arms reached far beyond a Forge World and its star system to distant outposts, Expeditionary Fleets and client worlds tied together by patronage or ancient treaty or pacts of allegiance. From its number the synod would choose several of its own, well-versed in the arts of destruction, or with proven battlefield experience, to operate as the Taghmata's command structure. Such commands were much sought after by many Magos, both for the power and prestige they would bring, and for the potential for acquisition of new knowledge and reward they offered.
In practise a Taghmata could be of greatly varying size, disposition and scope, the nature of which was often determined by the role it was called on to serve. Before galactic civil war was to rock the Imperium, the Taghmata was primarily mustered as a purely defensive measure, commonly when a Forge World came under direct attack. On Forge Worlds such as Tigrus and Phaeton which came under frequent assault owing to the proximity of hostile xenos forces, this led to powerful and highly-experienced Taghmata formations which effectively became standing armies, while others such as the isolated Stygies might go for many standard decades without external threat, and so when needed Taghmata protocols were required to be enacted afresh. Smaller Taghmata elements would also be raised and formed during the Great Crusade to arm and equip Explorator expeditions, to garrison outposts in hostile or hazardous regions of the void. They were also formed more rarely to provide armed diplomatic escorts or deputations to the Expeditionary Fleets and Rogue Trader Militant fleets. The latter two needs, however, were primarily the province of the specialist military commands of the Mechanicum not loyal to any single Forge World: the Titan Legions, the Ordo Reductor, the Legio Cybernetica and the Skitarii of Mars.
Pre-Heresy Mechanicum Forge World Hierarchy
The following is an exemplary illustration of the military-feudal organisational structure depicted in the abstract of a trans-Martian Forge World, as rendered by the Office of the Principia Militaris of the Great Crusade early in the first decade of the 31st Millennium.
- Archmagos Intendant (Planetary Governor) - An Archmagos Intendant was given equal rank to an Imperial Commander and Planetary Governor, with full executive, temporal and spiritual power over their domains, with notional fealty only to Mars and the Emperor. Note that various alternative nomenclatures for this title are used on different Forge Worlds (e.g., Hierophant Technis (Ryza), Gnostarch (Antioch Majoris), Fabricator Potentate (Tigrus), Vox-Omnis (Incaladion), Revered-Comptroller (Phaeton Prime).
- The Holy Synod of the Lord Magos (Ruling Feudal-Clerical Oligarchy of the Forge World) - Each member of the synod is a magnate and sub-ruler of their own domain or forge-fane on the Forge World, as well as a high-ranking priest of the Cult Mechanicus, tied to the larger web of the Forge World through a complex network of alliances, preference, arcane technological specialty and religious rank.
- Notional Synod seniority by title in order of power:
- The Archmandriture (Chamber Cardinal)
- The Archmagos
- The Magos Majoris
- The Magos Ordinary
- Notable Divisions of Techno-Arcana among the Synod commonly included:
- The Tachmata Omnissiah - The Tachmata Omnissiah was a military command protocol enacted in times of war or to create a detached military formation varying in size from sub-division to macro battle group, constructed by predetermined configurations of retainer troops, Tech-priests, war engines and support systems, placed under the command of a number of Magi of the Synod and commanded by Magi/Archmagi designated "Prime".
- The Legio Cybernetica - Sacred orders of Tech-priests devolved into cohorts charged with the construction and use of Battle-automata, existing both as fully independent structures and sub-factions owing either pacts of mutual support or alliance with the Synods of major Forge Worlds.
- The Magos Militant/Secutarius - Lower ranked Magi as well as assigned Tech-priests and prelates of militant sub-cults of the Mechanicum utilised by the Taghmata as a field command and control cadre. Each will commonly possess their own acolytes, retainer forces and sub-units owing then direct fealty.
- Principal Tactical Divisions of the Tachmata
- Associated Orders & Sub-Cults Militant - Composition will vary greatly depending on the Taghmata disposition, role and the tendencies and alliances of the governing Forge World Myrmidon Cult, etc:
- Indentured Labour Units
- Adseculatis Modified Troops
- Bio-Alchem Cadres
- Tech-Priest Lacyraemarta Covenants
- Cyber-Hybrid Carnivora
- Munitoria Logis - Provender of Munitions and Wargear, Servitor and Drone Cohorts. Assigned to Taghmata service.
- Signatus Avox
- Lexmachanicus Auditorii
- Enginseer Covenants
- Tech-thrall Combat Units
- Ordinatus Locum
- Technographica Determinus
- Bonded Cybernetica
- Bonded Tech-priest Covenants
- The Autokrator
- Ground Armour
- Pioneer Forces
- Mobile Artillery Units
- Tech-Guard Regiments
- The Knight Houses of the Questoris Familia - The ruling noble houses of the Knight Worlds form their own unique culture and traditions which have become closely linked with the Mechanicum over time. Households often deploy alongside the Legio Titanicus in support.
- Principal Tactical Divisions of the Tachmata
- The Basilikon Astra - The division of the Machine God's servants tasked with the construction, use and operation of voidcraft and interstellar vessels. This order's divisions by their nature control the outer reaches of a Forge World's star system and so stand apart from the planetary synods, but are still tied to them by dependence and ancient tradition.
- The Skitarius (Tech-Guard) - Ancient standing armies of elite cybernetically and genetically engineered troops, originating on Mars and principally loyal to the office of the Fabricator-General. The Skitarii, also known as the Mechanicum Protectors, are not members of the priesthood, but follow their own unique martial traditions and sub-cult of the Omnissiah. Skitarii regiments maintain entirely separate structures of organisation and tactical deployment outside of the Taghmata and are assigned at the behest of the Lords of Mars.
- The Prefecture Magisterium - Doctrinal covenant of the Machine Cult charged with preserving dogma and the persecution of techno-heresy. Magisterium Cohorts and hunter-killer claves are maintained on all Forge Worlds under the authority of the planet's Archmagos Intendant.
- The Legio Titanicus - The division of the Titan Legions, the Princeps and Moderatii of the Legio Titanicus are charged with the baleful right and onerous duty of mastering and maintaining the God-Machines that are the avatars of the Omnissiah's destructive wrath. The manifold Titan Legions are spread through the Omnissiah's domains as their shield and their strength, as well as operating as the hammer of the Great Crusade. The Legio Titanicus form an ancient military society existing in parallel with the Mechanicum priesthood, including their own support structure, domains and military retainers (Scutarii).
- The Ordo Reductor - Mendicant order of Tech-priests devoted to the art of siege craft, demolition and mass destruction. The Ordo Reductor is essentially nomadic, gravitating to areas of intense warfare, but maintains links to major Forge Worlds for resupply and support.
- The Horus Heresy - Book Three: Extermination by Alan Bligh, pp. 200-231