 Whilst the heroism and treachery of the emperor's legiones astartes often rings the loudest amongst the histories of the great crusade and the heresy that followed, it would be a poor, oculus investigatus who discounts the countless others who lived fought and died during the great and terrible years of both and a poorer one still who would ignore the participation of Terra's sister planet, Mars. Not simply the artificers or munition men of the greatest human endeavor of all time, Mechanicum of Mars fielded a vast array of armed forces during this period of history, in some cases with greater degrees of variety, efficiency and lethality than their imperial counterparts. No then, that this is a record of the origins, structures and wartime dispositions of the Tagmata Omnisya, the holy soldiers of the machine god. Despite dwelling ostensibly and in most imperial centric histories in Terra's shadow, the domains of red Mars were once as numerous, prosperous and populous as the homeworlds. Isolated from the rest of humanity during the long dark of the Age of Strife, the Forgeworlds owing fealty to the red planet were forced to fend for themselves in the deep terrors of old night, fending off the despoliation of predatory Xenos races, the ethereal onslaughts of warp creatures. Those that flourished often did so due to their abilities to defend themselves, and once the expeditionary fleets of the great crusade reached their stellar shores, these belly-coast kingdoms found themselves subsumed into the great mechanized apparatus of the Mechanicum. While Terra had its war council and the diverse other governing bodies of the Imperium that spread outwards beyond this, it remained in its totality a secular military dictatorship under the beneficent gaze of the Emperor of mankind. The Mechanicum was altogether different, a holy order, a technocracy, a fusion of church and state and industry. Although the Martian fabricator general held a seat by the Emperor's side, Mars was given control of the totality of its domains within the borders of the Imperium, a symbiotic relationship established under the Treaty of Olympus. While the worlds of the Imperium were under the direct governance of Terra, the many forge worlds of the Mechanicum were more disparate, independent polities that owed a sort of feudal loyalty to the Lord of the Red Planet. The degree of this lordship that Mars exercised varied vastly. Some planets were bound by absolute writ, satrapies to the seat of the fabricator general themselves, while others, the bonds of field tea, were altogether weaker, with rivalries and disagreements both scientific and theological, stretching the definitions of loyalty as far as they would go. This was in a very real sense, a product of both Mars' nominally weaker political and military power, compared to that of Terra and her Astartes legions, but also a facet of the Mechanicum's very foundation. The regime that had united the Red Planet during the horrible millennia of the Age of Strife had been a grassroots, or rather dust-roots, political and religious movement during its inception. The first tech priests were holy men, binding the roving clans of Mars together in veneration of the machine god, uniting scattered domains to fend off the ravages of the techno barbarian hordes and rampant thinking machines. Deals, treaties, alliances, all were the stock and trade of the Mechanicum, from its very inception. For the resources of the Red Planet were scarce, and it was always deemed by the eminently practical Mechanicum far more favorable to simply bring a polity, its resources, and more importantly its knowledge, into the fold by as peaceful or bloodless a means as possible. Whereas the Emperor upon Terra had launched his unification wars from the barrel of the first bolter, the Mechanicum had united Mars under their sway through means subtle, often as overt. This persisted for their entire history, right up until the Treaty of Olympus and beyond, when during the Great Crusade the real politic approach of their system was extended to newly found forges. These lost domains of Mars being slowly reunited with wider humanity were often negotiated with painstakingly, only to be deemed a war target in cases of the most extreme recalcitrance, or worse, tech heresy. What this would mean in many cases was years of bargaining with forges who had held fast throughout the depredations of old night, only to find the red-robed emissaries of Holy Mars arrive in system with demands of fealty. A powerful forge world would well-ken their status as a vital imperial and Mechanicum asset. The reunification with the forge of Phaeton, for example, led to a feud of reputations that almost came to open conflict, while Thrice cursed Xana managed to secure almost complete autonomy of not only its local galactic volume, but its very technological knowledge base. It can be said that the Mechanicum was less a regime and more of a shared culture and a heritage, indeed an obsession, all given political form by economic and religious projection. The concepts of duty and fidelity were often quite secondary to the more practical or even esoteric concerns, and so the forge polities of Holy Mars formed a feudal mirror empire to that of Terra, and a fractious one at that. Within this web of treaties and fealties were the forge worlds themselves, and indeed groups and alliances of forge worlds. Each were microcosms of the Mechanicum at large, networks of planet side and orbital domains and subdomains, which claimed territory over not simply physical space but knowledge and learning as well. The masters of each, the Arch-Majos and his subordinate Magi, held total authority over life and death within their spheres of influence. The human multitudes under their rule tools, wielded by them to achieve whatever personal goals they may have. Everything from increasing production quotas to the development and manufacture of fearsome combat engines, to simply serving as tech chattel in the field of battle itself. In a similar vein, these feudal lords controlled their armies and war machines of their domains, outfitted and equipped in accordance with their masters' inclinations or specializations. Thus they all served their forges as teachers, factory overseers, researchers, political governors, and generals all at once. These Arch-Majai and the forces at their disposal were the Tagma, the component materials from which a Tagmata can be formed. They were, in their own way, akin to the solid metal muscles of an engine, the many forming the whole, the far flung and disparate constituent pieces working in concerts to achieve one shared goal. As it was with the Mechanicum at large, so it was with their sacred Tagmata, whose very name, in the Omniceia's lingua tecnis, may be transliterated as that which is divinely ordered for war. No two Tagmata were ever identical. For each forge vein under the banner of Sacred Mars is as different from the next as night is today. This being said, there are broad similarities in how the feudal hierarchy plays out upon each Tagmata's formation. Each forge world has at its peak an Arch-Majos intendant to give them their most broad imperial title. Similar to imperial planetary governors in both rank and role, all held total executive control over their domains, be the forge located on a single world or spread out over several. Often these individuals were inheritors of grand traditions stretching back millennia, and bore such archaic titles as the Hierophant Tecnis of Riza, the Nostarch of Antioch Majoris, and the Vox Omnice of Incaladion. The Arch-Majos formed the head of the forge's local Synod, a council of the most highest ranking of Magi. As with the figure above it, these Synods can be formed in ways as unique as conceivable, for there was no one qualifying factor that could land one a position upon such a council. It is a ruling feudal clerical oligarchy, a collection of minds diverse and powers yet more diverse. Members could hold their seats by virtue of their skill at arms, the specialization of their knowledge, study, or skills, or simply by virtue of them being the best administrator the forge possessed. It was and yet remains perfectly common for Synods to have masters of Skitarii rubbing shoulders with a genitor Magi fresh from their gene vats, across from logisticians churning out reams of data from enhanced craniums. Notable divisions of the Tecno Arcana within these Synods ranged from the Hesfertari, Metallurgicus, Mirmidex, Lacrimalis, Alchemis. The Mechanicum truly were the masters of human knowledge, no one domain of science remaining unstudied. Every single Majos upon these councils would command a wealth of earthly power, and herein lies the most crucial difference between the Mechanicum and the modern Adeptus Mechanicus. While echoes of the feudal nature of the old Mechanicum remain today, the Adeptus Mechanicus currently has an inviolate chain of direct command downwards from the fabricator general. The Mechanicum however operated much differently and much more diffusely. Fieldy was owed, yes, but it was a quixotic thing, prone to shifts in political, economic or religious power. The fabricator general would entreaty, not command. It was a complex and frankly unstable web of odes, promises, favours, lineages and relationships that, while a necessary aspect of Mechanicum reunification and scientific progress, did make the process of ruling such an empire, if it can even be called that, a significant challenge, and one that was the ire of Mars' imperial counterparts, functioning as they did under the very direct military junta government of the emperor and his war council. The Tagmata is thus less an organisation and more a protocol, a declaration at a time of need instead of having standing armed forces, as to attempt to establish a hierarchy of command amongst the synods and their Arch-Majai and their Arch-Majai would have been functionally impossible, given the Mechanicum system of government. Instead, the Tagmata was a collective agreement made for the good of the forge and its interests, with member Majai contributing soldiery, automata and war machines in numbers they and the synod deemed appropriate. Through the protocol, a Majos of the Synod would be placed in overall command of the assembled Tagma, with other Majai then placed subordinate to them. Under the Tagmata would fall total command of as diverse a collection of warriors and machines as a forge may command. Common constituent elements were generally structured by the specialisation of the various Majai militant, also known as the Secutarii. These subcults and prelates, as well as their forces, varied wildly, and all according to a forger's individual capabilities. For instance, those of the Lacrimora would command and control the forgers at Secularis Tecthral cohorts, as well as bio-alchem cadres and packs of slaved Psi Carnivora. The Munitoria Lages were responsible for the munitions and equipment upkeep, as well as servitor control, while the Autocrator maintained ground armor forces and self-propelled artillery. While each Tagmata's bonded automata were often employed, the full forces of the Mechanicum's battle Autonoma fell under the purview of the Legio Cybernetica. Cybernetica were a formation apart from the forge, responsible for the shepherding, development and maintenance of all divinely sanctioned machine intelligence constructs. And while possessing a substantial degree of independence in their own right, nevertheless engaged in the same type of agreements and felties that all constituent Pan Martian elements did, leading to their aid often being pledged to Tagmata when needed. Distinct from the Tagmata in independence similar to the Cybernetica, yet again bound by odes and compacts, where the Basilicon Astra, Mars' fleet at arms, the Skatarii Tech Guard legions, the Knightly Houses, the Collegia Titanica, and the Ordo Reductor. Again, while all nominally and ultimately owing their fealty to Holy Mars, the ties that bound these elements together were disparate, and the relationship to any one Tagmata impossible to summarize, a nighthouse of the questorus Mechanicus, may literally share the same world and bloodlines as their forge, while the legio of the God engines may have only pledged a passing degree thanks to services rendered by a world's tech priests during the repair and refit of their Titans. Ancient traditions permitted Tagmata to request the aid of Basilicon ships, while the mendicant ruinators of the Ordo Reductor tended to pick theaters where their unique skills and destruction could be most valuably employed. In many cases, the invocation of Tagmata protocols reached far beyond a forge world sovereign planet to all mechanical realms within its star system and beyond to even more distant outposts, expeditionary fleets and client worlds, all tied together by the parent forge's patronage. Just as in practice, a Tagmata could vary greatly in size, disposition and scope, so too could the nature of the role it was called upon to serve. In great crusade terms, the Tagmata Mechanicum was primarily congregated as a purely defensive measure, generally when a forge world or its domains came under direct attack. On forge worlds such as Mighty Phaeton, which came under frequent assault owing to the proximity of hostile Xenos forces, there existed a surplus of very experienced Tagmata formations which effectively became standing armies, while others such as remote Stygies might go for many decades without ever encountering any external threat. So when needed, Tagmata protocols often required to be enacted afresh, causing much debate and jockeying for political power amongst the Synod. Smaller Tagmata elements could also be raised informed during the Great Crusade to arm and equip Mechanicum explorator fleets to garrison outposts in hostile or hazardous regions of the void, and albeit far more rarely, provide armed diplomatic escorts or deputations to the Great Crusade's expeditionary fleets and rogue trader militant flotellers. Should all of this ring to Imperial citizens, a blizzard of incomprehensible overlapping and doubtlessly contradictory elements? Well, it was. Hark to my words already spoken. The Mechanicum was less a regime and more of a shared culture, heritage and obsession given political form by economic and religious projection. It was, compared to the Imperium, perilously fractious. This disunity was rendered into terrible proof with the advent of the Horus Heresy. The Warmaster's treachery clove the Imperium in twain, so too did the Mechanicum schism. Already rife with strained feudal ties, religious and scientific disharmony, and in some cases barely contained hostility, the Mechanicum's web of alliances ate itself alive, with Forgeworlds choosing sides by the dictates of centuries or millennia old obligations, as often as they did for actual loyalty to the Emperor or the Warmaster. Suffers of civil war engulfed the galaxy. The Tagmata, previously an organ of defense, became just as frequently a means of attack. For whatever reasons, the Archmaegios desired, be it personal or political. Almost even more so than the Imperium, the multifaceted domains of Mars were in a battle for their very survival, with some actively siding with loyalist or traitor forces and directly participating within the conflict to earn their place in whatever order may come of it, while others simply clove their own independent path, renouncing oaths and severing ties only to find themselves being attacked on all fronts by those eager to claim the spoils of such would-be kingdom's defeats. In such desperate battles were sinister sciences and long-thought-last secrets revealed, and the blackest terrors of old night loosed upon the galaxy once more. Alas, such dark tidings must wait for a record of their own. Until then, Ave Imperator, Gloria in Excelsis Terra. If you'd like to receive more updates about the channel and any future videos, you can contact me or follow me on Twitter, at oculusimperia. 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