 Treachery is, on occasion, a thing of circumstance. As shown with the previous record concerning the legios estobiacs of the titan legions, which can be accessed in this archival stack should need be, it can be the result of circumstances entirely beyond one's control. With others, the decision to betray seems, frankly, inevitable. There are, across the span of human history, those of us to whom perfidy comes easy, a natural evolution, if you will, of our base state. Whether this is dictated by circumstance, character, or a mix of the two is moot. The only thing that is inevitable is the dagger in the back, the plunging hand of betrayal. We can question why. We can attempt to scry the histories of these heretics for answers. We may even find some. In the case of the subjects of this particular chronicle, such an effort seems wasted. It is hard to imagine their fate having any path save for the one they walked their engines upon. Scant anything within their actions or histories point to the possibility of any conclusion other than the one that was. Nonetheless, duty demands that I try, and I am nothing if not a diligent servant to my imperial duty. Know then, that this is a record of the titanic betrayers of the Caligia, the Death's heads. The Legio Mortis. There were few, in the early days of the Imperium, and even fewer now in this darkest of Millenniums, who can count their histories and honors in the standing that the Legio Mortis once did. It is likely one could have counted upon one's digits the organization's remaining extant whose foundations lie as far back as theirs, for the origins of the Legio Mortis lie within the origins of the Mechanicum itself. During the benighted Age of Strife, as apocalyptic warp storms cut humankind off from its vast galactic territories, the Sol system descended as those of its now lost stellar empire did into bloodshed, horror, and civil war. From Mars, sister planet to Terra, humanity's first off-world colony was not spared this. Strife bled across the heavily industrialized world as the various forges, corporations and polities that made up Martian society competed and eventually fought for the now scant resources which had previously fueled the world. From the materials that had stoked the production, to food and water that simply kept Martians alive, all were now in short supply. Desperation made animals of the peoples of Mars, and the ensuing wars led to an even greater tragedy, the destruction of the planet's terraforming machinery. Mars reverted back to how she had ever been, a rust-red wasteland. Now one choked with the fumes of belching war machines and rendered even more toxic by rampant use of atomic, chemical, and biological weaponry. From the ashes of centuries of bloodshed and horror, a new force emerged on Mars, the machine cult of the Mechanicum. While their full rise will be detailed in a later record, the Mechanicum was set aside from the various warring techno-barbarian tribes rampant thinking machines and hideous sigh cornivora by their singular unity, brought together as they were by a religious worship of the divine within the machine. This unity allowed them to slowly but steadily subsume Mars under their control, aided, however, by their technological mastery of secrets long thought lost to history but preserved amongst the ranks of their priesthood. One of these secrets was the creation of Titans, gigantic bipedal weapons platforms. Amongst the first engines were the Legio Mortis, one of the original three Legios founded upon the surface of red Mars in an age before the Mechanicum even commanded her fully. Mortis, along with the Legios Tempestus and Ignatum, formed the Triad Ferum Morgulis, the first three Titan Legions in human history. Mortis' role in the earliest years was twofold, with both stated aims being simple and direct. Firstly, they were to be the guardians of the fabricator general, the ruler of the Mechanicum, sentinels to his personal domain. Secondly, they were to, without hesitation, reproach, or mercy, commit to the annihilation of any and all life, human, alien, or machine that threatened the machine cult. This twin role, as both Praetorians and Executioners, was one that Mortis set themselves to with grim determination. They were ever at the van of the Mechanicum's early tagmata, their engine-manipals walking in support of early skitarii cohorts and slaved cybernetica robots. Their success was unquestionable, for they laid waste to the fabricator general's enemies, both without, and sometimes necessarily, within, with a precision that appeared simultaneously both cold and gleeful in its totality. The pitch black and dried blood red of their livery became a byword across the red sands for unrestrained destruction, for none would stand against the engines of Mortis when they began to walk. The legio itself became increasingly insular and cold, even to their brothers, amongst the triad ferrum, liaising little with representatives from the other two legios, unless circumstances absolutely demanded it. It was a situation, somewhat understandable, given their place at the fabricator general's side. On one hand, one must doubtlessly maintain a distance from one's fellows, since one may be their executioner one day. It appears, however, legio Mortis enjoyed this aspect altogether too much. The honor of being the personal legio to the fabricator general was one they were eager and quick to remind others of, and an authority the princeps of the legio would often wield in order to secure their engines' favorable births, transports, or repair priorities. Their distance from their sibling legios and later their scion legios only grew more so, becoming a fierce rivalry bordering on outright animosity and hatred in the case of the legio ignatum. Even the legios' territory on Mars became a physical representation of their isolation, with engines from both ignatum and the neighboring legio tempestus forbidden by sacrosanct treaty from walking upon it. Subsequent to the union of Terra and Mars, and the signing of the Treaty of Olympus, and by the outset of the great crusade, the legio Mortis was the imperium's most numerous titan legion, by sheer weight of the political clout they wielded on Mars itself. Admitting this, Mortis titan maniples were often assigned to the most prestigious imperial expeditionary fleets, notably including the 63rd expeditionary fleet under the command of 16th Primarch, Horace Lupercow, of the Lunawolves. As the crusade expanded outwards, so too did Mortis' numbers and reputation continue to grow. Their victory role includes some of the greatest triumphs in crusade history, both due to their vast presence in the crusade, but also their undeniable skill and combat abilities. The chained fury of the legio, previously used in uniting Mars under the machine cult, was now turned upon recalcitrant human regimes, mutant hovels, and alien empires. Had they ever shown restraint in destruction previously, any shred of this was now abandoned. The executioners of Mars laid waste to all before them, and the galaxy trembled before the tread of their engines. That being said, old rivalries, old animosities, these are things not easily shocked. Mortis' princeps quickly developed a reputation for viewing legios from lesser forges as distinctly inferior to those of Mars, by sheer virtue of their birth world, and interactions between those of the Red Planet and other legios were often fraught by the naked contempt among Mortis' engine crews for their upstart cousins in the rest of the Caligia Titanica. Mortis' cold and calculating nature would often extend to ruthless use of those titans from other legios placed under their nominal command, by virtue of Mortis' prestige, age, and experience. Likened by some as being akin to how Astartes legions, such as the 4th Legion Iron Warriors, utilized Imperial Army support, the now infamous example of this was during the Imperial Compliance Campaign on the planet Anarchizeta in the Shedim Drifts. The Aeldare of craft world Moor-Rioi were holding Imperial forces at bay with such stubborn opposition that Horus and the Lunawolves petitioned their attached titans of the legio Mortis, together with mannipals drawn from the legio Furians, Tiger Eyes, legio Osedax, Cockatrises, and legio Ataris, Firebrands, to walk upon the world and annihilate the Xenos foe. As the battle raged around them, Mortis, in overall command, ordered the engines of Ataris to launch a series of probing attacks under the guise of gauging the enemy's Titan class strength. Firebrands were indeed successful in this attempt, arguably far too much, as they were rapidly engaged by a superior number of life and terrifying Aeldare engines. The legio Furians ordered to guard their flank rapidly disengaged, leaving a full demi legio of Ataris surrounded. The Imperial war machines were annihilated, with only a single warhound class Titan making it back to the crusade lines, bellowing hails of the Mortis engines that were supposed to have come to its support. The battle's aftermath was revealed that this had been a ruse concocted by Horus himself to draw the full forces of Moor-Rioi away from the craft world itself and leave it vulnerable to a spear-tip assault from his Lunawolves. It would appear almost certain, as far as this chronicler is concerned, that the legio Mortis utilized its standing and the relatively lesser one of the Firebrands to ensure that their engines were not placed in harm's way, preferring instead to sacrifice the upstart legio Ataris. There does, however, exist times during Mortis' history that the legio dearly wishes were forgotten by the tides of time, notably their actions during the Battle of Prospero. Assigned to prosecute the sub-fane of the Forge world of Chou Arcad, members of whom had been deemed traitorous by association with the 15th Legion Thousand Sons, Mortis found itself engaging a dozen engines of the legio Zestobiax, vastly underestimating the skill in defense these engines of the Iron Vigil possessed, and the advantage given to them by their psychically imbued mind-impulse unit core systems, the Mortis Manipulse, under the command of famed senioris-princepts Maldus Terrain, were all but annihilated, saved only by Constantine Valdor's grudging commitment of the Emperor's own titans, the Ordo Sinister, to the field. The legio did their utmost to bury this incident, redacting records, reassigning officers, or converting the surviving crews to servitors, ex-switch, given the pal of secrecy the entire Prospero campaign existed under, were likely entirely unnecessary. Even to those of us granted access to the records, the conflict at the Arcadian sub-fane is itself a footnote, subsumed by the importance of the conflict between the 6th Legion space-wolves and the Thousand Sons. Mortis, however, could not bear the slight against their honor, coming down hard on any and all they felt were to blame for the debacle. Indiscriminate became the watchword for how Mortis would comport itself in those later years of the Crusade. Their methods of war-making grew even bloodier, ever more destructive, with the Titan Legion renowned for their brutality, now becoming known for the cruel pleasure they appeared to take in the apocalyptic ruin unleashed upon planets that stood in their way. Yet, despite widespread concern with their methods amongst those of the Divisio Militaris, none could gain say their unassailable political power, which the Princes of Mortis would wield in much the same manner as they did the Volcano cannons and plasma annihilators mounted upon their engines. Quick to anger, stubbornly prideful, and utterly disdainful of any who they saw as lesser than they, Mortis was a political wrecking-ball, commandeering transports, gain-saying repair orders, and securing deployments to prestigious campaigns with no subtlety. Indeed, the scorn with which they treated Imperial authority speaks to a deeper issue within the legio, their true loyalties. Mortis had never made any claim to be loyal to the cause of the Imperium. He never had. Mortis' allegiance lay, as it had always lain, at the feet of the fabricator general of the Mechanicum. The Mechanicum's goals lay in tandem with those of the Imperium was a matter of convenience for Mortis, and an excuse to travel abroad upon the stars and earn the glory and rewards that came with it. Unlike many of their fellow Titan legions, they viewed the Great Crusade with a detached cynicism, never being the ideologues that others, such as the legio presagius, were. In their role as wardens of the cult Mechanicus, they were tasked to be watchful for any potential enemies to the person of the fabricator general, and this, the legio assumed to encompass allies of the era. If a Titan legion could not trust, and indeed, actively feud with, those beside whom their order had been founded, what hope did those removed from the Mechanicum by ideology, religion, or politics have? By the outbreak of the Horus heresy. The legio Mortis was the most numerous and most powerful Titan legion within the Imperium, to the extent that the Divisio militaris had some difficulty gaining an accurate read upon their numbers, this being a facet both of their widespread deployment and the legio's own demand for operational secrecy, contradictory though the concept may be for engine class war machines. Estimates extant from the period vary wildly, placing Mortis' numbers at anywhere between 150 and 300 Titans. The true extent will likely never be known, is that the legio had extended its range to encompass the majority of the crusade's active front lines, ensuring it was placed in the most prestigious of campaigns and amongst the forces of the most celebrated commanders. It was this tendency, as well as their undeniable records of victory, that had seen them become the Titan legion of choice for Warmaster Horus Lupercal, and had ensured that they were in an ideal position to become the primary vanguard of the traitor Titanicus. The renowned Imperator class Titan, D. S. E. Ray, took part in the atrocity on Istivan 3, and later the great betrayal upon the sands of the dropside massacre, becoming the first Titan to fire upon loyalist imperial forces. And, across the galaxy, Mortis' engines turned their wrath upon the unsuspecting forces of the Imperium. Ironically, this was not even done at the behest of the Warmaster, but, instead, the Fabricator General. In typical Mortis' fashion, it was only the decision of Fabricator General Kelbor Hale to side with Horus that swayed their guns, but swayed them so terribly it did. The heresy would etch the name of the legio into the annals of the Imperium forever, as a byword for terror, destruction, and betrayal, as their appetite for annihilation would only grow in tandem with the madness that would come to define them. Until such a time as their later histories may be explored, Ave Imperator, Gloria in Excelsis Terra. And if you're looking to keep in touch with the channel, get regular updates, you can follow me on Twitter, at ButstuffKaiju, or check us out on Discord, a link will be in the description and on the channel page.