 could tell of what these fallen sons are now, of what their betrayal brought them, and how power and pride mutilate nobility. But then anger would darken my words, and hide the truth that you, my lords, so crave. I will not pretend to understand the reasons that drove my brothers down the path to ruin, that is for others to tell. Instead, I will seek to remind my lords of what these warriors once were, and so show the height from which they fell. It has been oft remarked by chroniclers of ages past that all wars begin with a single shot fired, the first bark of the first firearm to be discharged in either rage, in defense, or in betrayal. It is a pleasing narrative device that allows the human brain to grasp what is never, ever, a simple occurrence. Rare is it that war is driven by a series of clear and concise motivations. Even should it appear so upon the surface, scratch that utter layer away, and you will find beneath the murky depths of forces social, economic, ideological, religious, and many, many more besides, all of whom powering two or more sides towards conflict. It takes work, rigorous applications of scholarship, education, learning, ability, and patience to construct a moving image of what truly leads to a war. Your humblest servant has previously attempted to do so, insofar as one can, dwelling as one does in a millennium benighted, using a mind ever besieged by the tendrils of insidious insanity. The Horus heresy is a conflict so large, so calamitous, so all-consuming that even today, the walls of this palace within which I am privileged to dwell, yet retain the scars they took from the guns of the traitors. This planet, this holy terra, counts as its foundations of its high cities, the dust of Metropolis's yet more ancient demolished in the fires of the 16th Primarch's ambitions. Our Imperium rots from without and within, a juggernaut of an empire sustained merely through sheer inertia. We are born of heresy, all of us, the impact of the truest betrayal in human history continuing to reverberate ten thousand years later, when Horus Lupacal and his eight brothers brought all human progress to a crashing halt. He died in those years. That age of darkness. We will never recover. Imperium endures, but it will never rise again. It is a gasp for air, stretched out over thousands of years. The future is hopeless. It is broken. There is nothing left. And if this long, slow death were to have a first shot, the opening salvo in a war that sundered a species, upon a single world was it heard. No then, that this is a record of the beginning of a war that claimed the lives of uncountable trillions of a day that sealed the fate of humanity forevermore. A record of the Istvan III atrocity and the beginning of the Horus heresy. Located in the northern reaches of the Ultima segmentum, the Istvan system was a small but for the region relatively important celestial body containing not one but two worlds capable of sustaining human life. The system had been settled in the depths of the dark age of technology. Tens of millennia before the rise of the emperor upon Terra. The presence of these worlds on ancient stellar cartographical charts led to the region being marked for survey by the scout flotillas and rogue trader expeditions that ran ahead of the emperor's great crusade. And all signs pointed to the continued survival of humanity upon these worlds. Having been somehow spared the depravities of the Age of Strife, Istvan had seemingly maintained an advanced industrialized society, albeit one seemingly without either the capability or will to mount spaceflight missions outside of their solar system. The reunion between Imperium and Istvanian was not uncommon during the great crusade unfortunately fraught. The auto-Catholic culture that had endured the millennia of old night was one steeped in mysticism, one that thus reacted with dismay and defiance to early entreaties from the Imperium, which of course demanded the renunciation of all spirituality and the immediate cessation of all religious practices, all in accordance with the emperor's secular imperial truth. As with all instances of such defiance, hostilities were inevitable. The emperor and the Imperium's offer was binary. Priority was given to the system's capture, given the size of its human population, the location in an otherwise empty northern tracks of Ultima segmentum, as well as a potential wealth of its industrial base. It was an ideal staging ground for future crusade pushes out into the galactic north, not to mention its value as a sectoral hub in centuries to come. Excessive collateral damage was actively argued against by the War Council. Any losses of infrastructure or population would damage the Imperium's prize. Accordingly, the assignment for its capture was granted to the 19th Legion Ravenguard, and their Primarch, Corvus Corax, who had recently concluded operations in a relatively nearby volume. With the surgical precision the Legion was famed for, the Ravenguard struck from Istvan's planetary knight, seizing key points in the capital of Kry-Vanek, roughly translated as Coral City. Within hours, before the sun had even crested the proto-Hives boundaries, the senate that had ruled Istvan for centuries was a bombed out ruin. All of its magistrates that had defied the Emperor's offer were either captured or dead. Pockets of resistance to the Ravenguard were swiftly dispatched, Corax following the orders to avoid collateral damage to the letter. Defiance guttered out. Compliance was achieved, and relatively bloodlessly. Istvan, like thousands of worlds before it, joined the Imperium unwillingly but quietly, as off-world Imperial Army garrisons arrived to police the new colony, and the Ravenguard departed to bring similar fates to some other far off world. The records of compliance, a form of after-action post-mortem report required by the Imperial Regime for all military engagements undertaken on human worlds, was filed by the 19th Legion quite promptly. The report made no reference of any esoteric or external influence upon the world, its population or its ruling regime. Nothing xenos, malefic, or psychic. The potential retention of religiosity was highlighted, with acknowledgement that the few violent holdouts were zealous devotees not only of the culture's primary faith, but sects and cults marginalised by mainstream Istvanian society and dogma. It was noted that many of these saw the downfall of the ruling regime as a sign of its inherent weakness and corruption. That the ideological vacuum created by official dogmas collapse could potentially lead to opportunistic growth by these cults, should they choose not to heed the Imperial truth. All of this was, of course, a problem now for the compliance regime, not the Legion as a start is. Converting the population was the work of Imperial iterators, many of whom were now ceded amongst the Istvanians to convert them to the secular light of the Emperor's writ. As this was taking place, the Coral City was selected as the Imperial planet's capital to allow for a symbolic transition of rulership. The shell of the presenter's palace was raised anew as an Imperial cast from Fortress to house its garrison, alongside which a new starport was constructed by Imperial Army pioneer corps and the adepts of the Mechanicum of Mars. Given that the system had required force to affect compliance, Imperial policy dictated the governorship be handed to internal personnel rather than any local body. The man selected was Vardis Praal, formerly a major of the 11th Lastron Rifles, who had transitioned out of active service and into the political sphere as a career bureaucrat in the court of Ultima segmentum. Given his experience in both the military and political wings of the Imperial regime, Praal was officially considered a safe pair of hands to guide what was intended to be an important linchpin of future development in the system's local volume. Early records of said development prove that the faith of the Imperium was rewarded in Praal's reforms. Istvan flourished under his governance, becoming a peaceful and prosperous developing Imperial world, an almost model example of how to deliver compliance to a previously defiant human population. This was, of course, not last. Several years into Praal's reign, conditions in the warp in Istvan's local region began to grade. It is not uncommon for the Imitarium to develop squalls or storms, quite the opposite, but typically they do not last for more than weeks or months local planetary time. In the case of the Istvanian sphere, the storms lasted for years. The system had always been isolated in terms of galactic distance from other worlds. During the Age of Strife, it needed no outside connections nor desired them. Now, with Imperial rulers, the severance of that vital off-world connection was to prove incredibly challenging. Supplies rarely arrived. Many of the ships were simply forced to turn back rather than brave the tumult of the warp. Reports on the status of the system would only reach the Administratum upon Terra after many months, and often only fifth or sixth hand from a rogue tradership. All of them spoke of rising instability, of civil disorder, of Imperial iterators murdered by crowds of fanatics. Praal had apparently chosen to meet this fervour by ordering the complete destruction of cultural works deemed religiously tainted, as well as a demolition of several ancient sites of mystic significance. The reasoning it was said was to break the subtle cultural hold the old faith of Istvan continued to hold over the populace, but reports did not say whether or not this had been successful. All that could be corroborated was that the cults mentioned in the Ravenguards after action report persisted, and that the most dangerous amongst them were being led by individuals bearing a title steeped in Istvanian mythology, the gothic translation of which was rendered as war singers. Istvan quietly slipped out of all contact with the Imperium, with Praal being trusted to get the situation under control and matters of more pressing logistical concern diverting the Administratum's attention. It was not until six years after the last official word from the system had been heard that, by chance, a single patrol ship of the 14th Legion Deathguard, on its way out of Neogeden, intercepted fragments of an astropathic transmission. The ship's own astropath was rendered near Catatonic by the information they received in their dreamfuge. Istvan III was in open rebellion. Vardis Praal had fallen and was leading the revolt himself. He had become corrupted by the religion of the world, had become a mutant, had become a ciker, or both. The Coral City was drowning in blood. All non-believers would eventually be put to death, and an Imperial world would now be cast down by the religious fanatics that rose like vermin from its sewers. Such an event could simply not be countenanced. Some who heard it blanched at the very idea. An Imperial world? A compliant world? In rebellion? Such a thing simply did not occur within the boundaries of the Emperor's light. These individuals were, of course, unaware of the long history of sedition that occurred during the Great Crusade. The examples were not many, it must be clarified, but they did occur. The lack of official acknowledgement of them was, of course, entirely to plan. None defied the word of the Emperor, or the manifest destiny of the Imperium to rule every world within the galaxy. Certainly none lived to tell of it, and their stories never made it to anything even remotely approximating greater awareness. Recidivism on compliant worlds was put down with maximum force, swiftly and thoroughly. What was perhaps unique about the Istvan system was the scale. Billions of humans lived within the system, and it seemed now that open rebellion had been the case for years. Word of this had not yet leaked beyond the information obtained by the Death Guard, and none within the Imperium's various bodies, who were privy to it, would see it go any further. The stain knowledge of such an uprising would cause upon the Great Crusade was unacceptable, lest it breed sedition elsewhere. Introducing the idea that the Emperor could be defied? Impossible. Worse still, the appointed Imperial Governor was the figurehead of this defiance. The crimes of Istvan and of Pral demanded the swiftest of all responses and the most merciless of all punishments. When the information reached the course of Horus Lupacal, 16th Primarch, Jean Sire of the Sons of Horus, a Stardes Legion, and reigning Warmaster of the Imperium in his father's stead, his was a fury most righteous. Pral would pay dearly for this outrage, declared Lupacal, vowing to make a bloody example of the Governor and the people of Istvan for their truculency. This was, of course, barely a hint of what lay within the coils of the Warmaster's true plans. As any student of history will be no doubt aware, the Warmaster Horus had by now fallen under the thrall of the primordial annihilator, the so-called Dark Pantheon of the Chaos Gods. The process of the Primarch's corruption had been a long and serpentine one, the tendrils of the Dark Gods infecting Lupacal's ego from without, while the resentments for the course of his life, for the course of the Imperium, festered within. Your most humble servant has previously attempted where possible to chart the course of this personal downfall, records of which may be perused by Acolytes, should they so wish. But suffice it to say, by the time the news of Istvan reached his ears, Horus was totally resolved upon his course of betrayal, and he was far from alone in this. Behind him, proverbially speaking, was the Primarch Lorgar Aurelian of the 17th Legion word-bearers, whose own fall to the gods had taken place many years before his brother, and his legion wholly committed to their new deities. In treaties, pacts, and deals most foul, had already been sealed with the lords of the 20th Legion Alpha Legion, 4th Legion Iron Warriors, 8th Legion Night Lords, Alphaeus, Pertorabo, and Conrad Curse, respectively. Curse was at this point in his history all but renegade to the Imperium, having ordered the destruction of the erstwhile homeworld Nostramo before taking his legion into the deep void, and almost severing all communication from the Imperium. Pertorabo, similarly, had wrought in his rage great suffering on the people of his world of Olympia, embittered as he was by an ego bruised from centuries of perceived injustices and mistreatment at the hands of his brothers and his father. Of the motivations of Alphaeus Omegon, well, those can only be gassed as by chronicles such as mine. Suffice it to say, the serpentine lord of the 20th was never one to do anything by whim. These legions, and Lorgar's, were, thanks to the warmaster's efforts, involved in campaigns in precisely the galactic reaches they were needed by him, but their time would come soon. More immediately, Horus' attentions were turned to the mustering of the 14th legion Deathguard, 12th legion World Eaters, and 3rd legion Emperor's children, all of whom had been ordered to gather by his side. Counted amongst this muster were the Lord's Mortarian and Angron of the 14th and the 12th. Fulgrim, the Primarch of the Emperor's children, had been dispatched on a mission of utmost importance to Horus personally, but in his stead was represented by Lord Commander Eidolon of the 3rd. These three, as with all the brothers Horus counted upon, shared the warmaster's grievances with their father, although for deeply personal and idiosyncratic reasons of their own. Mortarian, for example, had grown disgusted with what he saw as the rank hypocrisy of the Emperor, as well as perhaps his own hypocrisy for serving a ruler he saw both as a tyrant and a sorcerer witch, similar in too many respects to those he had spent his early life overthrowing on Barbarus. Fulgrim's desire for perfection in all things had devolved into a twisted obsession, aided in no small part by the eldritch influence of a curious sword he had obtained during the pregation of the Xenos Lair. Angron's hatred of his father had been a cancer in his souls since their first encounter, and his decision to follow Horus had perhaps been one of the easiest the traitor sons of the Emperor had made. In total, almost half the surviving sons of the Emperor had pledged to the banner of Horus. Of the others, well, the machinations of the Warmaster were far-reaching indeed. Magnus the Red, the crimson king of the 15th Legion Thousand Sons, had fallen months previously in conflict with his brother Leman Russ of the 6th Legion. The burning of Prospero, as the battle had become known, was a direct result of Magnus's defiance of the Emperor's laws, it is true, but the death of the Primarch had not been explicitly the intent of the Master of Mankind. That Magnus had fallen, removing one of the most powerful of the Primarchs from the proverbial board, may or may not have been the direct result of Horus's intercepting of Leman Russ' capture orders. But regardless, it had played into his hands very well. Not only were the Thousand Sons no longer a consideration in the grand scheme, the wolves of Russ had also been badly mauled by the battle, sustaining heavy casualties and dramatically reducing the threat they posed to the Warmaster's plans. Lupacow knew many of his brothers would simply never turn to his side, nor see his vision for the Imperium, and so had spent quite some time ensuring they would be in no position to challenge him once his heresy was revealed. The Lion of the 1st Legion Dark Angels, inscrutable and ironclad loyal 1st-born son of the Emperor, had been diverted to the far Galactic West by the Warmaster's orders. The Blood Angels, the 9th Legion, and their Sire, the Great Angel Sanguinius, had disappeared in the Cygnus Cluster, pursuing a mission on, yes, Horus's wishes. The 13th Legion Ultramarines were preparing a muster in full at Calth, Pristine Jewel World within their Legion realm of Ultramar, the Primarch Rebut Gulliman, having been issued instructions to await the arrival of Lorgar and the Word Bearers, that they might heal their fractious relationship through campaigning against a nearby Orcoid Empire. The 7th Legion Imperial Fists and 5th Legion White Scars were beyond the grasp of Horus, but neither were of a special consideration for the Warmaster at this time. The Fists and their Primarch, Rogaldorn, were stationed in their near-totality upon Terra, acting as Praetorians for the Throne World. The White Scars and their elusive Primarch, Jagatai Khan, were primarily grouped in the long-running Chondax campaign. The tendrils of Horus had crept into the Scars long before, through fraternal Warrior Lodge groups, and the Warmaster trusted that, in the event that the Legion did not sway to his side, their impact upon his plans could be mitigated. Finally, schemes for precisely what would befall the 18th Legion Salamanders and 19th Legion Ravenguard were already well in hand. And as for the 10th Legion Ironhands and their Lord Ferris Manus, the Warmaster trusted that Fulgrim's mission would go according to plan. The largest of the Loyalist legions had been diverted or placed upon courses of doom. Others were accounted for, tracked, ensnared. This is, of course, not even accounting for the billions of Imperial military personnel, ships, war machines, and sundry other assets that fell under the scope of the Warmaster's command. Those you could count on were placed in favourable locales, granted access to the latest and most advanced technologies and gifted boons diverse. It was a game of literal regicide, only now played with pieces uncountable across a board unimaginably vast. By Horus' strings did the unwitting Imperium dance, and upon its shores was a storm unbelievable about to break. With the ignorance of the masses on his side, Horus' mission on Istvan appeared for all the world to be a punitive expedition that he described it as, although one that admittedly was in such a force as to stun any who read the disposition manifests. Sons of Horus, the deathguard, the world eaters, and the Emperor's children were all gathered in their near totality, all to take a single system. Such a force of arms had not been seen since the Eleanor campaign, and that had been waged against the single greatest Xenos threat that the Imperium had encountered since the Rangdan Xenosides. To quell an uprising of civilian zealots, it was madness to think such an army was necessary. For a start, his legions was a force to conquer half a galaxy. Some whispered of the mad excessiveness of Horus' expedition, quietly wondering whether the ego of the still new warmaster was demanding such ridiculous extravagance. But Lupercal remained firm that such an army was a necessity. It delivered in no uncertain terms the scope of the doom that would befall any other seditious populations, should their defiance be so marked as to earn it. In total, some 200,000 Astartes were present, as well as significant quantities of the Exertus Imperialis regiments, Mechanicum Tagmata, Night Houses, and Titan God Machines of the Legios Audax, Vulpa, and Mortis, and, at their head, three Primarchs, Horus, Mortarian, and Angron. Fulgrim's delay was notable but not unexpected, with Lord Commander Eidolon trusted by his Primarch, if few others, to serve correctly in his stead. A council was convened aboard Horus' flagship, the Vengeful Spirit, known to us largely thanks to scraps of surviving records from intrepid Imperial Remembrancers, who, for months now, had found themselves increasingly sidelined from the activities of Horus and the legions he counted as closest to him. Once they were welcome in his presence, now they were scorned. Ostensibly, this face-to-face meeting, breaking in Horus' new Lupercal's court, was a confluence of brothers and commanders to discuss strategy that would be undertaken once the fleet moved in system. In actuality, it is far more likely that within the walls of Horus' court, upon that day, the Warmaster assayed the commitment of his kin, and outlined precisely how they were to prepare for the betrayal that was at hand. An Astartes legion is not, as some may believe, a monolithic thing. Behind the iconography, the matching panoples, the shared genetic lineage, they remain composed of individuals. Individuals that, yes, are psychologically maimed as part of their genetic ascension, indoctrinated to comply to orders, and to serve a cause higher than their own quasi-immortal lives, but they are individuals nonetheless. Despite the direction their gene-sires may elect to take a legion in, the Primarchs were deeply aware that many Astartes under their command would balk at the idea of treachery, that their loyalties would remain with the Emperor, the Imperium, and the ideals of the Great Crusade. Since his own fault the predations of the Dark Gods, Lorgar Oralian had been at work to mitigate this. The fraternal Warrior Lodges were of his idea-born. Ostensibly, a rankless meeting of brother Astartes, in actuality they were perfect vectors for the poisonous ideology the 17th Primarch had embraced to seep into the legion as Astartes. The embrace of the Lodges by the Sons of Horus had been widespread, and they were met with varying degrees of success across other legions. Not only, indeed, did they serve to sway marines to the cause of the traitors, they additionally helped to identify those whose loyalty to the Emperor could not be counted upon, and would eventually supersede loyalty to Primarch. These Astartes would prove once the plans of the Warmaster and Kin were revealed a massive potential problem. It is believed that, at this Council of Primarchs, Horus unveiled to the assembled precisely how he intended to deal with that problem. East Van, despite the forces arrayed against it, was not expected to be a simple pushover campaign. What scraps of intelligence the Imperium had obtained spoke to a potentially malefic taint present in the rebellious populace. At the very least, the existence of enemy psychers was assured, those aforementioned war singers. Such potential danger demanded a massive landing in arms. The Estevanians had never possessed much in the way of militarized spacecraft prior to the initial compliance action, and none remained in orbit to trouble Horus' fleet. A mass infantry drop, formed to appear for all intents as one of the Warmaster's famous spear-tip manoeuvres, would plunge via drop pod and flyer directly into the coral city, denying the villainous prowl any time to mount a unified planetary defense. The assault would be formed of infantry divisions drawn across all of the attendant legions. None would have much in the way of air cover, as the enemy possessed no airborne war machines, and there would be minimal armored vehicle presence, save for some tanks and support vehicles drawn largely from the deathguard. What sparked curiosity for those selected for the initial wave was a manner in which it was seemingly being selected. There was little in the way of any sort of overall coherency. The startys were seemingly being plucked almost at random from units, and said units were often finding themselves assigned to a different consul, or captain, than they had previously been subordinate to. For whatever inscrutable reason, the Warmaster was playing fast and loose with the chain of command not only of his own sons of Horus, but three other legions besides. None, of course, had any authority to gain say this, had any even sought to. The Warmaster had absolute authority to conduct the affairs of all military assets under the Imperial banner, and while the behavior appears to have raised eyebrows, nothing in the way of formal protest was lodged, even by legions at word to put it mildly quite prideful when conducting their internal affairs. There was one notable exception in this case. Tenth Company Captain of the Emperor's Children, Saul Tarvitz. During the capture of an outlying Istvanian orbital outpost, Captain Tarvitz, an exemplary line officer of the Third Legion, had witnessed what he believed was a display of antithical genetic modification amongst the senior staff of his Legion. Lord Commander Eidolon had, according to the journals of Tarvitz, displayed some sort of biological enhancement that had allowed him to project sonic waves from his throat and mouth at such a rate and frequency as to destroy the bodies of the enemies arrayed against him. While the primarch of the Emperor's Children was not present and the Lord Commander had ordered his silence upon the matter, Tarvitz's suspicions about errant behavior amongst his Legion's command cadre led him to examine the assignments for the upcoming invasion, noting he himself had been assigned to the planetfall but Lord Commander Eidolon was stationed to remain in orbit. In fact, very few senior staff from any Legion and none of the primarchs were included in the initial duty rosters, not even the bellicose angron of the world eaters. Tarvitz was unsure as to why this was the case, especially in this instance that a warrior so egotistical and oft veined glorious as Lord Commander Eidolon was to be seemingly denied glory of leading from the front lines, wishing to explore the matter deeper but not to disrupt any sort of ongoing muster nor draw undue attention to himself. Tarvitz requested leave to remain in orbit from one of the drop's most highly ranked Third Legion Astartes, the Contemptor Dreadnaught Ancient Rylanor, who himself was preparing to lead the Emperor's Children in the drop. The suspicions of Saul Tarvitz won Astartes amongst hundreds and hundreds of thousands. Would soon come to play a part in history, the man himself would scarcely have conceived possible. Four specific target zones had been highlighted for the invasion. The Precenter's Palace was the primary objective, given that it was a seat of Imperial Governance and the ancient center of Istvan's Theocracy, as well as the most likely location for the traitor Governor Prahl. The seizure of this was selected for the Emperor's Children. To the world eaters was given the responsibility of capturing a series of plazas adjoining the palace, where resistance was expected to be both heavy and projected to converge, allowing the Butchers of the 12th ample ability to indulge in their murderous skills. The Imperial constructed Western Bastions were selected as the Death Guard's targets, with the goal of eradicating all those who dwelled within, and if capture was rendered impossible, that they be reduced to rubble. Finally, the Sons of Horus were tasked with the seizure of a massive Templum complex in the city's east. Known to the population as the Sirenhold, the historic buildings had been effectively abandoned during early Imperial colonization, mostly under the strict terms enforced by the iterators and by Prahl. But orbital reconnaissance had registered not only significant human presence in the complex, but exotic and unidentifiable energy readings too. If the degenerate religions of Istvan were here at work, this would appear to be the locus of both their arcane effort and their faith, making this perhaps the highest priority target of any invasion force, wishing to both break the military and spiritual hold of an enemy. Resistance at the Sirenhold was expected to be fierce and powerful. The War-Singers, the enemy Psykers spoken about in intelligence reports, had been encountered by Eidolon and the Emperor's children during their preliminary engagement in the system. The Psyker witches had reaped a toll upon the Astartes, but it was quite heavy before being brought down. Starports, typically selected as targets to allow for the landing of reinforcement and resupplies after an initial wave, were only marked as tertiary objectives. Clearly, the Warmaster expected a four legion planetfall to succeed in crushing the enemy in near totality in one swift manoeuvre. When it came, the wrath of the Imperium hit Istvan with the force the world had never experienced, not even in those bloody days of early compliance. From orbit, the ground targets were hammered again and again by land strikes, a blizzard of blinding light beams that lasted, but for a brief moment, until, riding upon the atmospheric hell their firing had wrought, a steel rain of drop pods plunged planetside. Resistance was far, far heavier than any projections had made. The Deathguard reportedly made first encounter with enemy forces, assaulting the western fortifications. The Istvanians were recognizable as imperial aligned, or at least their uniforms were. In aspect, they were peered now mad, mutilated things, almost inhuman incontinence, corrupted, it was assumed, by the sinister saucery of the war singers, possibly even under some form of telepathic thrall. Certainly, they threw themselves at the attacking Astartes with what seemed like a complete lack of fear. Faced with the Deathguard, they not only turned Divisio Militaris' standard issue heavy weaponry against their attackers, but basilisk artillery and Malkador heavy battle tanks too. Against another Legion, this may have presented some challenge to overcome. To the Deathguard, it was yet another engagement where their famous fortitude would allow them to overcome. The 14th Legion's initial landing had brought them in so close to the Istvanian defences as to deny their artillery even minimum range. The torrents of small arms fire and support weapons fire poured onto the Deathguard as they emerged from their drop pods, phased them not in the least. Wading through the storm that greeted them, Deathguard terminators and support squads camely and indefatigably targeted and demolished enemy bunkers. While the tactical squads of the legions swept their trenches with radiological and chemical weaponry, annihilating anything living with extreme prejudice. The fate of these bulwarks was fully sealed by the arrival of a demi-manipule of Titans from the legio-mortis, whose god-engines pulverized what was left to dust. The methodical sweeping of this sector was not, to put it mildly, replicated elsewhere. In the plazas of the central districts, the world-eaters slaughtered their way through all that stood before them. Cohesion lost as the senseless melee filled the dense streets of the ancient city. Overhead, however, precision landing vectors identified by the 3rd Legion were followed to the T. Purple armored fliers of the Emperor's children circumnavigating the presenter's palace seemingly effortlessly. Their assault ramps disgorging squads of Astartes in perfect formation, deep into the heart of the enemy's administration and defense. Finally, across the city, the Sons of Horus attack on the Sirenhold was being conducted with that Legion's famed tenacity and ferocity, but the complex rapidly degenerated into a multi-story firefight of epic proportions. The entrenched Ystivanians using the Labyrinthine Temple complex to punish the invaders for every step forward. It was here, in the Templam Fane of a culture thought consigned to history, that the war singers first made themselves known to Imperial forces. The enemy appeared to be wielding psychic forces to manipulate sound itself, utilizing it to fly through the air, surrounding themselves with vibro fields to turn away small arms fire, and, most devastatingly, project sonic force in such a concentration as to shatter the Ceramite power armor of the Lugenes Astartes. Against the flesh within, even gen-hanced bone would turn to dust, modified flesh pulped to liquid by the songs of the war singers, whose presence additionally drove the half-mad armies of Ystivan into a form of cultic euphoria, serving as potent idols in flesh to this enemy. The arrival of the war singers upon the battlefield was felt not only by the sons of Horus, whom they were now arrayed against, but across the whole combat sphere. A psychosonic scream of shattering intensity was recorded city-wide, an auditory assault resistance to which was only possible thanks to Astartes' physiology and power armor. The autosensors of the latter throwing up sonic baffles against the sheer overwhelming force of the scream. Curiously, abominably, it affected the completely un-augmented and unprotected civilians of Ystivan utterly differently. The populous, native, imperial, both, regardless of alignment, had been cowering from the inferno of war that had engulfed their world. With the arrival of this scream, they, as one, rose from their homes in hideouts and flung themselves at the invaders with a fanaticism unbridled. Without any care for their lives, with mouths frothing and eyes wild, the charge of the civilians took the Astartes by utter shock. The world-eaters, enmeshed within the civilian reaches of the city, felt it first. Dozens, then hundreds, then hundreds of thousands, a living tide of humans threw themselves at the chain-axes and lady-eye of the 12th Legion. Never one to deny any a bloody death, the world-eaters happily oblige these thrall civilians, these mad things. But by sheer weight of numbers were being forced back to their landing zones. An Astartes, even alone, is easily a match for a hundred mortals. But isolated, surrounded by 200 rabid hands clawing and seeking any crack in their ceramite, any makeshift weapon which might pierce it, even an Astartes may be brought down by a feckless swarm of corrupted minds. Bolters and support weapons ran dry. Even chain weapons became clogged with splintered bone and pulped viscera. The world-eaters were well accustomed to what, by the definition of any other age, would amount to war crimes most foul, but so rarely against an enemy that apparently did not care whether it lived or died. The battle, the slaughter, was hard fought. The day carried in large part thanks to the actions of two battle groups elsewhere. The first, led by 10th company captain, Garvia Loken of the Sons of Horus, captured a bizarre, corpse-clogged shrine at the heart of the siren-hold, putting to death its war-singers, while in the center of the presenter's palace, Captain Lucius of the Emperor's children battled the traitorous Vardus Praal in single combat. Warped beyond all recognition, his once proud imperial armor contorted with eldritch psychosonic weaponry and augmentations. Praal did indeed appear to be the leader of this corruptive cult. In desperate battle did Lucius slay him, the swordsman's peerless skill eventually overcoming Praal's warped sorcery. With the death of this magister thing, this once-Pral, the hold of the psychic Gestalt appeared to break, no longer motivating the enemy upon Istvan. The abominable cacophony ceased, as did its hold on the population, many of whom appeared to fall catatonic or simply mad thanks to its sudden dispersal. The rebellion, as it had been, was no longer functioning. The mutilated militia, bereft of a motivating force, were mopped up with ease, butchered as they wandered dumbstruck through the ruined city. It appeared that victory was won, hard fought, yes, but the triumph of the warmaster's retribution had been delivered. Or, so all those upon the surface believed, aboard the vengeful spirit, Horus, the warmaster, had gathered in the main viewing gallery a curious audience, the remembrancers and exactors of the Imperium, the artists, poets, chroniclers, bureaucrats and aficiants attached to the 63rd Expeditionary Fleet, who had, since the fateful events with the inter-ex and upon Daven, been increasingly sidelined, treated with hostility by the Imperial military and the Starty's aboard. Aware that such a summons from the warmaster could not be ignored, the gathering was a large one. Almost every single civilian aboard was present, including the remembrancers Euphrates Keeler and Mercedes Olaton and iterator primus Kiril Sinderman, although these three were making all efforts to disguise their presence, going to issues Keeler was having with her status in the expedition's burgeoning cult of the Emperor Deified. Elsewhere in the fleet, Captain Saul Tarvitz had made a discovery that had, fundamentally, broken his world. He had uncovered orders that the weapons bays of the entire fleet had been ordered to be loaded with exterminatus-grade weaponry, specifically the monstrous life-eater virus. These were quite literally weapons with which worlds could be killed, an ultimate sanction hitherto reserved for planets deemed utterly lost to Xenos infestation. Nothing survived them. They were end times things, blasphemies created by the darkest minds of humanity and its most hateful epochs. Tarvitz drew the only conclusion available to him. Guided by his hearts, he commandeered a thunderhawk gunship, knowing his message would never reach those on the soil of Istvan through conventional means. His escape was immediately noted and deemed a massive security breach by Lord Commander Eidolon, but Tarvitz's headstart meant that only one ship lay within a possible intercept volume. The 14th Legion frigate Eisenstein, under the command of 7th Company Captain Nathaniel Garrow. A Terran deathguard with a long and admirable service record, Garrow was known to Tarvitz and was now placed within an impossible situation, ordered by his legion and others to fire upon his friend or to listen to the pleas that friend was making. Although communication logs of what was said between the two have been lost, it is confirmable by Garrow's later testimony that he ordered the Armada Imperialis fighters pursuing Tarvitz to be destroyed, refusing to fire on the thunderhawk as it plunged planetside. It is safe to say that without this one decision, history itself may have taken an entirely different course. Abored the vengeful spirit, the gathered civilians beheld a figure they had not seen in months or years. Horace Luprika armored in night, bedecked in wolf pelt. Possessed, it seemed to many, of a conviction that went beyond even his typical resolve. In the viewports outside, inexorably, the battleships of the fleet were assuming a position over the planet below, an arrangement for all the world appearing to be for orbital bombardment. Like vast metallic cetaceans, the vengeful spirit, the andronius, the firebird, the killing star, the conqueror, the war child, the gauntlet of spite, the indomitable mill, all arrayed themselves. Horace bade the Remembrancers watch, his voice quiet yet reaching to all ends of the vast hall. They wished to see war, he declared. This is it. With that, droplets of light fell from the fleet, tiny bright pinpricks falling planetward. In pure silence, the first of the virus bombs detonated above the coral city itself. Air bursting munitions, they were intended to seed the atmospheres, upper and lower, with great clouds of their payload, and they did this within human uncanny precision. A single bomb could devastate a small world. Istvan was drenched in hundreds. The plumes of life-eater agents fused into the great clouds, racing outwards across the planet's atmospheric systems, carried upon the wind and air with terrifying speed. From orbit, it appeared for all the world as if stains were spreading across the pearl of the world. The assembled Remembrancers grew quiet as they beheld the sight. Some began to weep softly. From so high above it was all soundless. Planetside, the air was filled with screaming. Human, astartes, fauna, the virus claimed them all. The virus claimed everything living, from the mightiest transhuman warrior to the smallest bacterium. It was phenomenally, utterly effective, reducing anything organic to a rotting slurry in seconds, as it ate at the fundamental molecules of all biological life. Everything that encountered it perished in pain that went beyond words, perhaps mercifully only for seconds before they too were turned from a living thing into black necrotic tar. Where once a planet of billions had stood proudly dwelling within a diverse biosphere, all was rendered in minutes, a toxic choked hellscape of decaying matter. Grey desolation clad in gelatinous filth could now be seen from the skies as the corruption consumed the whole world. Six billion souls lost in minutes, weeping civilians aware, perhaps dully of what was happening, observed this all, catatonic in grief so that they did not notice the sons of Horus that entered the chamber now. The great crusade is over, Horus is said to have declared at that moment, to the horror of all the assembled. Perhaps they were now aware of what this meant, yet had such realization came it was too late for them. The Warmaster ordered their deaths at that moment. Artists, writers, historians, one almost wonders if the act was a symbolic one for him. The death of a culture only being born wrought at his hand. His astarties carried out his will with ease. Thousands of civilians that had gathered to hear the 16th Primarch speak were all dead in under a minute, torn to bloody shreds by bolters and chainswords of the Dugenez astarties. Horus did not even watch. Turning his back to the slaughter, he is said to have beheld the stained and ruined Istvan and issued the four words that changed the course of time itself. Let the galaxy burn. In the silence of the Void, a single land strike was born of the vengeful spirit. The eye-searing beam shot towards Istvan. It was not aimed at any sight in particular. It did not need to be. Its purpose was as match to kindling. The twisted, malicious genius of the life-eater virus was, effectively, as a two-stage weapon. In minutes, the virus could render all organic matter into slurry and miasma, a soup stewing amidst what remained of a world's biosphere. The sheer amount of flammable matter and gas this created was almost beyond comprehension, when it needed but a single spark. This was one that Horus had tossed upon the pyre. The firestorm that the land strike created was instantaneous. From the point of its impact, a circle of flame, issunami of destruction sped across the surface of Istvan. Its passage consumed in fire and ruined the remnants of what had once been life, the people, the animals, the plants, all now fuel for an apocalyptic incineration of an entire world. The sheer atmospheric chaos this created was another layer to the destruction, deluges of megastorms and overpressure, pounding what structures were left to dust and debris, even as the rocks they were made of were seared by flame. From orbit it appeared as if a new star was being birthed, an atmosphere of an entire world alive with dancing, chaotic flame consumed by a corona of red and yellow and orange annihilation. Those in orbit observed Istvan burning in the heavens, watching in morbid fascination or satisfaction at the unparalleled atrocity that is the death of an entire planet. Soon would the fires die down, the sub-atmospheric conflagrations guttering out as the organic slurry they had consumed was fully spent. An ash strewn orb now hung in the void, stripped in minutes of all life. The only sounds of the world now formed from the tortured atmosphere venting its pain in storms. Istvan was now a dead world, and that dead world was a statement. Horace Lupercal, 16th Primarch, warmaster, had spat upon his oaths and his kinship. No longer was he the emperor's son, and to this father's imperium would he visit the same destruction that this world had felt. Yet, for all the warmaster's infinite malice, for all his meticulous planning, there had not quite lain perfection until such a time as this record may continue. Ave Imperator, Gloria and 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 Oculus Imperia. Otherwise, please like, subscribe, comment, let me know your feedback, and as ever, thank you very much for watching.