 By Mark 21.00, 0.00, it could be considered a safe statement that many of the survivors of Calth had resigned themselves to death under the light of the Viridian star. It should not be taken as a surrender to Meldonkale, indeed far from it. Histarities of the 13th Legion, ultramarines, continued to comport themselves with the utmost discipline and dedication, relentlessly applying themselves to the immediate practicalities of their situations, but for many their fates now seemed clear. Whatever recompense they were to earn would be bought from the enemy in blood and destruction, and they would count it good. All, however, was not lost. The battle was not yet won by the traitorous 17th Legion and their allies. As one has elucidated upon previously, the word-bearers, despite being in a position of near-total tactical and strategic superiority from the very moment of their betrayal, had, at least in base military terms, squandered this position in favor of their pursuit of matters altogether more esoteric. While the full extent of these eldritch machinations were yet to birth, it had allowed the 13th Legion an iota of room to regroup, reinforce, and begin to plan. The ultramarines, of course, were led by one of the greatest planners in imperial history, and Robert Gulliman, recovered now from his imprisonment in the thin atmospheric shells surrounding his flagship, was striving to develop the situation into something that would deliver his Legion from annihilation. The key to victory, or perhaps more accurately, the key to survival past the next several hours, lay in the usurped planetary defense grid. The thousands of weapons and placements, both on the planet's surface and in orbit, had been captured by the word-bearers earlier in the battle, and turned by the traitor mechanical to the command of Core Phaeron. Since then, the first captain of the 17th Legion had wielded the grid not only to punish ultramarine orbital and ground forces, but to murder the entire Viridian system. While slaved to traitor control, no significant muster of force could be managed by the ultramarines, as Core Phaeron would immediately retask the grid to punish and annihilate. Thanks to Marius Gage's recapture of the McCraggs Honour's secondary bridge, Gulliman was able to coordinate planning with the largest loyalist force that had established contact from the surface, that of 4th company captain Remus Ventanus. Ventanus had, during the course of the battle, linked up with mere Edved Toren, who was believed to be the most senior surviving Mechanicum adept on Calth. From Toren, the captain, and laterally his Primark, had learned that a data engine, potentially the only one on Calth not infected by pernicious scrap code, lay within the Landshear Guild Hall. This engine would allow loyalist Mechanicum to re-establish the newsphere, and thus control over Calth's networked weapons and placements. But this would only be possible if control was also taken from the data Overseer engine, currently being used by the word-bearers to command the grid. This engine locus was currently in Zetsunvered Yard, the last surviving orbital shipyard, and the base of operations for Core Phaeron. The attack on Zetsunvered would be led by Gulliman himself. While the Primark acknowledged that his role was as a general, not a warrior, he nevertheless stated to Marius Gage that he would not allow any of his sons to deny him the satisfaction of killing the first captain of the word-bearers with his own hands. Ventanus' attack began with a rapid advance in force into the ruins of Landshear City. The formations he possessed were heterogeneous, a diverse mix of imperial military elements. The majority was of the captain's own fourth company survivors, supported by Solar Auxilia, Exertus Regiments, and Mechanicum Tagmata elements under Majos Toren, and Skitariai Marshal Aruk Serutit. It was a motley assortment of survivors to be sure, swept up into Ventanus' mission by sheer luck and fate. The remnants of the Neride Tenth marched alongside Mechanicum Tag priests under the massive bulk of Shadow Sword super-heavy tanks, while at the vanguard Ventanus led a wing of Thirteenth Legion Land Raiders. Their first detected opposition was also their first kill, a sole warhound scout titan of the Legio Mortis. The engine was alone and unsupported. Its princess had clearly been granted leave to indulge their darkest destructive fantasies on Landshear City, and for this they would pay. Despite pushing its voyage shields to maximum, the warhounds' force bubble popped under a hurricane of fire from predator, whirlwind, and Sikaran tanks, before a pinpoint strike from a Shadow Sword ended its wretched existence. The portentous engine kill marked the start of the engagement. Ventanus' forces fell upon the Wordbearer defenders of the Guildhall with the fury of the betrayed. Ultramarine discipline and cohesion kept barely in check in the face of a fury most righteous. Wordbearer Gal Vorbach reaped a fearsome tally from the attackers, but the rage of Ultramar would not be denied. Ventanus' forces captured the Guildhall and delivered the Mechanicum to their work. Their success was buoyed by the arrival of new allies. The 111th and 112th companies, bereft of their command cadres, had been led to the Guildhall by a single sergeant named Anshiz, while Captain Aethon of the 19th company, so called the Honored, also arrived. A whole mortal host soon too made their presence known, led by Ultramarine tetrarch Eikos Lamiad, as well as the Honored Dreadmark Telemacrus. The reprieve, welcome as it was, would be short-lived. Allspecs' feeds registered a massive inbound enemy force, led by Hall Belloth. Despite the Mechanicum's possession of the Data Engine, the corresponding Overseer Engine in Zetsunvered had yet to be freed from Wordbearer control. Unless it was, the efforts of Ventanus' companies would be for nothing, and Hall Belloth's Wordbearers would annihilate them within the hour. Yet in orbit, the second half of the 13th Legion's desperate gambit was now underway. Gilliman himself led a teleport assault from the McCraggs honor to the Zetsunvered orbital. The flagship could in no way risk movement for fear of alerting the weapon's grid, so dangerous a maneuver was now the only one left at the Primark's disposal. The sheer range of the teleport would draw so much power from the ship, and shunt so much of it through the ancient systems that they would surely overload, rendering extraction by this method impossible. It was a final gambit, and was understood as such. Failure would see the Primark dead, Calth lost, and the Legion nigh exterminated. The risk was the only course possible for Gilliman. Without control of the weapon's grid, his Legion would simply die regardless. It was only a matter of time. The battle between the Primark and the Master of the Faith was unlike anything hitherto seen in the Age of Darkness. Corfeiron had ascended to becoming a debased Magister of the Powers of the Warp. He had drunk deep from the cups of sorcerous might, and the full scale of his present abilities were unleashed upon Gilliman as soon as the Ultramarines attacked the Command Center. Invested with the responsibility by Lorgar himself for the Calth operation, Corfeiron withheld nothing, blasting Astartes to ash with Warp spawned maledictions before turning upon Gilliman himself. Even the Primark was rendered near helpless before the sorcery of the Master of the Faith. Driven to his knees by a beam of blackest unlight, Gilliman was sprung upon by Corfeiron, who pressed the black flint of anathemae to his throat. This cursed dagger was one of the eight shards of the anathemae blade, forged by the Xenos Kinnebrack and stolen by Wordbearer's first chaplain Erobus at the outset of the Inter-X Crisis. The self-same blade had been used to mortally wound Horace Lupercal upon the moons of Davin, delivering the Primark to that world's sinister lodge priests for care. Its new blasphemous children had been wielded by several individuals throughout the Battle of Calth, and one was now poised to reap the life of a Primark. However, at the exact moment when the killing blow could have been struck, Corfeiron stayed his hand, instead choosing to whisper into Gilliman's ear an offer he had no authority to make, yet did so regardless. Theron promised Gilliman a place within the works of primordial annihilation, a place of great honor amongst the ranks of the Dark Pantheon's followers. All the 13th Primark had to do was pledge himself to the worship and devotion of chaos. But for his word, the Master of the Faith offered him a place within a new universal order, and all the power that came with it. Gilliman said nothing. His armoured fist canoned into Corfeiron's torso. The 13th Primark's response to the cillibent offer was to tear Corfeiron's still beating heart from his body, and cast its ruin upon the cold, metal deck. At the Lanshire Guildhall, salvation began to reign from the heavens. In blinding columns, Lance Beams seared Planet Word, but they did not impact the beleaguered defenders. The might of the Calth defense grid was turned instead upon the traitor host, and in an instant extinction had been turned to retribution. An immediate, planet-wide counter-attack was mounted on every major word-bearer force currently operational. Orbital strikes reigned hell upon the traitor hosts, punishing each and every one in extremis. Still reeling from the wrath of the defense grid, these forces were now set upon by vengeful loyalists. Astartes, Mechanicum, Exertus units rising up against their attackers in near unison. This was not just merely upon the surface. In orbit, word-bearer ships that had ruled Calth nearspace unchallenged now had the weapons grid turned against them. The platforms had been designed to fend off a threat approximate to a full battle fleet in proper standing order. The scattered word-bearer ships, which for a near full day had been gleefully hunting helpless targets of opportunity, were now annihilated in kind. Vessels of the 17th Legion that had centuries of service perished in instance, torn into by the unbridled fury of the weapons grid. Still choked with the carcasses of the Ultramarine's grand fleet, those perished loyalists in orbit were joined by the wreckage of their attackers. The sheer volume of debris the 13th Legion counter-attack now added to would create an artificial set of rings for Calth, the planet becoming encircled with the corpses of those ships that had fallen in the Great Betrayal forever more. On the bridge of the Infidus Imperator, it is known that Corpheron manifested shortly into the counter-attack. Still somehow alive in the aftermath of having his heart torn from his chest, it is believed the master of the fate survived through sheer mastery of Warpcraft. He was, however, apparently in no fit state to issue commands. It was the shipmaster of the 17th Legion craft, Antonius Antwark, that ordered the vessel's disengagement from the battle, reasoning that their contributions to the Betrayal and its arcane significance had been accomplished within reasonable parameters. The Infidus Imperator came about and made full burn for the nearest Mandeville Point. Bored the McCrags honor, its flight was immediately spotted by the Sensorium adepts and reported to Marius Gage, who in turn raised his victorious Primark on Zetsun Verid. Absolutely unwilling to allow the ship and presumably Corpheron to escape, Gilliman ordered Gage to mount an immediate pursuit aboard the honor. Both vessels vanished into an unknown Warp disturbance at the edge of the system. Their fates would remain unknown for years to come. Gilliman himself would not learn of the fate of his flagship, his first chapter master, or his loathsome enemy for quite some time, and indeed the full tale of this insane clash must be reserved for another record. Although the Ultramarines had mounted a stunning last-minute reversal of fortune, this was not victory by any means. The delegation of counselors, led by a group of Mechanicum adepts surviving fleet navigators and clearly traumatized astropaths, petitioned Gilliman for time, for dire portents had emerged that required the Primark's immediate attention. The Veridian star had, during the hours of the weapons grid being in word-bearer hands, been explicitly targeted by the 17th Legion, along with the remaining stellar bodies in the system that they had murdered. Likely through the use of specialized ammunition, the traitors had inflicted horrific damage to the star's fusion reaction. Whatever they had ceded into its mass, it had caused Veridia to begin outputting increasingly lethal levels of radiation. The poisoned solar winds were now beginning to pummel Calte's atmosphere, which had already been grievously wounded by almost a full Terran day of continual weapons bombardment and atomic attacks. Not only were its tectonics irreversibly impacted, the sheer amount of smoke unleashed by firestorms that still raged across its continents were choking the skies. The combined effects of the Mechanicum avowed would, within days, render the planet's surface utterly inviolable for human life. With full evacuation from the planet impossible due to the sheer lack of Legion vessels still operational, not to mention the time involved, the only recourse was the withdrawal of all the whalists still alive upon Calte to the subterranean arcologies. The planet was rich with a network of tunnels through its porous crust. During its development, many of these had been turned into arcologies, underground cities connected and linked with future expansions already planned. While far from ideal, they were well suited to immediately absorb all surviving civilians, astartes, and other humans, and could provide at least some shelter from the fury of the now poisoned Veridian Star. Captain Ventanus volunteered to lead this operation without hesitation. His fate now seemingly irrevocably bound to the planet, the Master of the Fourth Company announced over every open vox channel that this was a Primarch's directive. The fleet, or what remained of it, would embark to what craft they could, the remaining surface armor units, as well as what god engines of the Calesia Titanica were still operational. Even as this was being conducted, the navigators and astropaths of the Legion brought the Primarch yet more dire news, pleas for aid from across the entirety of Ultramar. Calth, it appeared, was the beginning of a much larger conflict. The 500 worlds were being assailed by, according to reports, not merely the wordbearers, but the 12th Legion world eaters, and their Primarch, and Gron. Dozens of systems and Ultramarine's forces were reporting the same dire situation. This was no less than a full-scale invasion. Calth, Gilliman grimly surmised, had merely been an opportunity to exterminate the bulk of the Ultramarine's Legion, allowing the traitors to then conquer and reave Nye unopposed through the jewels of the Eastern Fringe. In this, they had essentially failed. The Legion and its Lige were very much alive, and could be rallied, but the price they would pay, and had paid, was undoubtedly dire. Almost 120,000 Ultramarines lay dead, with a further 20,000 crippled and in dire need of Medicaid care. In many ways, the wordbearers had succeeded. It could hardly be argued that they had not. The final piece of information for Gilliman was altogether more difficult to comprehend in scope, but no less pressing for it. The navigators were reporting that the currents of the warp were becoming extremely restive, the tides of the Imaterium in significant flux. For whatever reason, these disturbances were centered around Calth and the Viridian system. At best estimate, the fleet's navigators surmised that the system would become cut off from the wider galaxy by an oncoming storm of unprecedented power, and that the storm may in fact be spreading outwards. Already capricious this past year, the rising warp instability sealed Gilliman's course for him. Once the final units could be embarked from the surface, those warp-capable ships would flee the system. At Calth Mark, 23.43.00, Remus Ventanus glimpsed to the surface of the world that he suspected would be his very last time. Loyalist Mechanicum elements, mostly the remnants of Arch Majos Karn Barberell's Tagmata, took the brunt of the final phases of the retreat, far more resilient as they were to the effects of increasingly debilitating radiation. Unfortunately for the Loyalists, the traitor forces still alive upon Calth had read the signs, and had heard Ventanus' proclamation. Where possible, significant elements of word-bearers likewise retreated to the Archaeologies. This marks the beginning of the Underground War, a near decade of conflict that would only conclude with the defeat of the traitors on Terra at the end of the Horus Heresy. The betrayal at Calth did not conclude in the manner of other battles in the Age of Darkness. Not only was the Underground War its dreadful successor, continuing the battles on the planet years after the initial shock of perfidy, the unfolding shadow crusade saw Gilliman immediately engaged as soon as the evacuation force made wake. Calth's tale is the tale of the heresy itself. The last of the 17th Legion was not purged from its tunnels until the fall of the Warmaster. The mark of Calth itself was kept running by the 13th Legion until approximately mark 219,479.25.03 during the scouring. When Captain Ventanus, hero of the Underground War, led the Ultramarines to Colchis, the homeworld of the word-bearers and Lorgar. With them, they brought death. A planet for a planet was scant recompense. Like the continued running of the mark, it was a thing of symbolism and little else. Of course, the purging of a warp tainted population was a matter of significance in the years of the scouring, but the real heft of the matter lay in the base revenge of the act. Symbols, as the Imperium had learned during the Horus heresy, carried significant weight. Crimes of Lorgar and his Legion could not be repaid in the simple death of one world, but Colchis' destruction yet mattered. For the word-bearers themselves, some scholars have speculated that the mark of Calth may yet still run, in the depths of the Great Eye or the Maelstrom, the countless pockets of blackest treachery to which their craven kind ran. The mark, too, was not merely that of Ultramarines' battle records or the obsession of the word-bearers while the Legion still lives. Colloquially, the mark of Calth was the name ascribed to severe radiation burns, suffered by the survivors of the Betrayal, and was caused by the poisoned light of the Viridian Star. The scarring was distinct and in many cases quite serious, but veterans of the battle would often forego skin grafts and Medicaid procedures, wearing them as a grim badge of honor. The mark, too, also refers to psychological damage endured by those who had survived the treachery of the word-bearers. The trauma of the attack was significant enough to brand itself onto even the psychoconditioned minds of the Ligiones Estartes. Survivors of the massacres formed groups apart from fellow legionaries who had, by virtue of chance, simply not been present at the conjunction. In the broader context, Calth presaged the wars of the Age of Darkness in ways that would only become evident in dread retrospect. While it was perhaps the last grand, full-scale display of the sheer surprise of concealed treachery, the utter devastation of civil war between Imperial military forces was now writ large upon the scarred, rent surface of an entire, fully populated Imperial world. A star system had been murdered in the space of a day. Billions lay dead in less than twenty-four hours. This was one system, one world. The battlefield to come was galactic in scale, until such a time as one may relate further tales of this benighted epoch. Ave Imperator. Gloria in Excelsis Terra. 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.