Legio Xestobiax - Legion History: Throughout its long Terran millennia of isolation and the turmoil of its more recent history, very little is known about the Legio's early years before it came to be the "Iron Vigil." As with most extant Titan Legions, it is presumed that the first of the Legio Xestobiax's war engines were part of the initial expedition that founded the new Forge World of Zhao-Arkhad. The Forge World's own existent data-archives confirm this, although no trace can be found as to which greater Forge World produced the first Titans of the Legio Xestobiax. In fact, no established Forge World of the ancient Mechanicum has been recorded to have despatched a colonial expedition to the galactic south.What little evidence remains indicates a foundation pre-dating the formation of the Imperium but cannot be more specific. From these truly ancient times, the Legio Xestobiax conserves a single reminder, the crippled Warlord-class Titan Munus Aeternum which now rests in the vaults deep beneath the forge-fane of the Supreme Domini on Zhao-Arkhad. The Munus Aeternum is not listed in the roster of any existing Titan Legion and the details as to which battle or battles left it in such a lamentable state have since been consigned to oblivion. Like many things concerning the Legio Xestobiax, its very existence thickens the mystery around the true origins of the Iron Vigil.Thanks to the Arkhadian Mechanicum, sources describing the first years on Zhao-Arkhad are more numerous. Several accounts relate how it was only through the devastating weaponry of the Legio Xestobiax that the first forge-fane survived against the hordes of macro-predators lingering in Zhao-Arkhad's tropical jungles. This means that very much from its inception as an independent Titan Legion, the Legio Xestobiax has been a defensive force against the multiple horrors that plagued the Zhao System, be they beast or xenos.Given the severely corrosive effects of Zhao-Arkhad's atmosphere, which even the hardiest materials could not resist, the Arkhadian Mechanicum quickly decided to relocate the Legio's headquarters to the moon of Arkhad III, with smaller garrisons spread on the other Arkhadian moons of Arkhad I and II in order to defend the Forge World's nascent lunar colonies. Intended at first to be a merely temporary solution, these deployments or "Vigils" as they were known, became near-permanent formations, each distinguished by the individual Vigil they upheld. Thus was the Legio's cognomen of "the Iron Vigil" born.While overall the Legio maintained its identity as the Legio Xestobiax, assignment to these individual Vigils became second nature to the Legio and many of their battle-honours memorialise only the Vigil the victorious Titans belonged to. For instance, the 14th Battle of Istiam Station -- a gruesome, destructive siege conducted by elements of several nomadic Aeldari fleets, or "craftworlds" -- is celebrated as a resounding victory for the entire Legio, but its battle-honour is borne only by the two maniples of the Istiam Vigil. This scattered deployment means that for much of its history, the Legio Xestobiax had never fought as a whole but had always stood guard above those Arkhadian colonies and forge-fanes they were honour-bound to protect.Theoretically, the Legio is commanded by a "grand marshal" as custom would dictate it, but the Legio's deployment leaves the grand marshal with little more than ceremonial or diplomatic duties, as in the field each Vigil is led by an officer with the rank of "princeps-warden." Some of these Vigils have stood unchanged for many millennia and may exist for standard centuries apart from the greater Legio and its home garrison of Istiam Station.Their solitary duties has increasingly led each Vigil to develop tactics, deployments or configurations best suited for the kind of terrain they were occupying -- some of them even developing traditions and idiosyncrasies of their own that set them apart from the greater Legio. As such, maniples of the Legio Xestobiax are used to relying on themselves and prefer to operate as small, autonomous units. As a result, princeps of the Iron Vigil tend to be more independent-minded than their colleagues from other Titan Legions.The Iron Vigil implicitly trusts the judgement of its princeps and gives them considerably more command leeway than other formations of the Collegia Titanica or the Adeptus Mechanicus. Because of the many Vigils it maintained, gatherings of all the Legio's princeps-wardens were troublesome to organise. However, the isolationist tendencies of the forge-fanes of Zhao-Arkhad and the Legio's lack of transport capacity made such events rare occurrences, even after Zhao-Arkhad's unification with the wider Imperium.During its many Terran millennia of isolation and solitary duty, the Legio Xestobiax has benefitted from its parent Forge World's acceptance of illicit practices in the domain of psykana-arcana and other related fields of study. To guarantee the survival of their homeworld, the magi of the Arkhadian forge-fanes had delved deep into half-forgotten and poorly-understood lore dating back to the Age of Strife that concerned fusing organic components with the technological creations of the Mechanicum. However, these magi also studied the strange artefacts they scavenged from the hulks of vanquished Aeldari Titans felled by the Iron Vigil. As such research had never been officially censured on Zhao-Arkhad, this led to the creation of proscribed techno-artefacts such as the Eminarii sub-type hybrid Battle-Automata.The Arkhadian forge-fanes tried to emulate the properties of the wraithbone cores at the heart of every Aeldari Titan. These strange devices are believed to conserve psychic imprints of their previous pilots, allowing the living crew to tap into the memories or even experiences of their forebears. In addition, wraithbone cores are far more effective at controlling a Titan than the standard Mind Impulse Unit used by the Collegia Titanica.The Arkhadian magi's efforts led to the creation of the Black Iron Core, which is still regarded as the greatest achievement of the Eminarii forge-fane and their Forge-Domini, Tacitus Proctor. These prototypes were fitted to the majority of the Iron Vigil's god-engines and had become commonplace by the time of the Battle of Prospero. The use of the Black Iron Cores allowed the god-engines of the Legio Xestobiax to operate with a far smaller crew than other Titans of an equivalent size class as well as enhancing the crew's reflexes and tactical prowess.By the time the Thousand Sons Legion rediscovered Zhao-Arkhad, the Black Iron Cores were still only prototypes. As part of the terms of their Imperial Compliance, a portion of the Legio Xestobiax would go on to serve within the Great Crusade, although due to their continued lack of transport for the Titans, their contribution was a modest one.With the new influx of materials, Zhao-Arkhad was finally able to expand the Legio Xestobiax's fighting force, by either producing a limited number of new Titans on their own world, or receiving several new models as gifts from the larger Mechanicum. The Legio Xestobiax was expanded through the creation of a Prosperine Vigil, a new detachment that was sent to the Thousand Sons' homeworld of Prospero to watch over a new sub-fane of the Arkhadian Mechanicum. It would be this Prosperine Vigil that would later be involved in the events of the Burning of Prospero.Whilst the entire Prosperine Vigil was ultimately destroyed during that battle, the Legio Xestobiax nevertheless bested and vanquished a detachment of the highly-decorated Legio Mortis, which was at the time considered the most powerful Titan Legion of the entire Collegia Titanica. Condemned by the highest echelons of the Imperium and the Mechanicum for siding with the first Space Marine Legion to defy the Emperor's will, the Legio Xestobiax was declared guilty of treason by association due to their allegiance to the Forge World of Zhao-Arkhad.True to their oaths, the remainder of the Legio -- believed to have numbered no more than 50 god-engines -- sided with their overlords of the Arkhadian Mechanicum but were little involved in the Horus Heresy, upholding their lone vigil and defending Zhao-Arkhad and its domains from those that would prey upon them.What truly happened during the Great Scouring is a matter of conjecture, and whilst the Legio Xestobiax was officially pardoned by the Imperium for not taking sides during the Heresy, the Legio was thoroughly investigated by a Metallican Assay taskforce and forced to relinquish all discovered hereteknical devices and technologies to the control of the newborn Adeptus Mechanicus.More recent records are almost devoid of any reference to the Legio Xestobiax other than that they have continued to uphold their ancient vigils into the present.