The Sanguinary Heresy: Paradise Lost

"And so the Arch-Betrayer Sanguinius led his sons against the loyal Legions of the Emperor of Mankind, revolting against His sacred dream for Mankind's ascension. Standing with the Angel of Blood were half of the Legiones Astartes, corrupt and vile, their fears and greed exploited, unaware that they had become pawns of the Dark Gods. It was only due to the exploits of heroes and martyrs that Terra withstood the Arch-Traitor's assault. Only through sacrifice of those who remained true to His dream was the Imperium able to emerge triumphant. The cost of victory was grave indeed, resulting in Our Divine Majesty sitting upon the Golden Throne, lamenting the Paradise Lost while His Immortal Soul acts as a beacon for all His people in this Dark Millennium, because in the void of stars only the sound of laughing gods can be heard."

Pre-Heresy: A Dream Ascendant

It was over and it was done. In the early years of the thirty-first millennium, the Master of Mankind had realised His dream, and had led humanity in conquering the stars themselves. First among the Imperium's vast armies stood the Legiones Astartes, His Angels of Death who knew no fear. Each Space Marine Legion was led by one of His recovered sons, the primarchs, demigods of war who conquered the galaxy in glorious reclamation of Mankind's birthright.

But the Astartes were not alone, beside them stood the Imperial Army, unrelenting in its nearly inexhaustible numbers of soldiers and warships. Alongside them tread the mighty God-Machines and Knights of the Mechanicum, ready to lay low entire worlds that dared to defy Mankind's manifest destiny. And in the shadows lurked the Officio Assassinorum, with unfathomable weapons ready to purge those unfaithful to the Master of Mankind's dream, willing to commit atrocities that few would stomach and even fewer would ever undertake.

With such a mighty arsenal at its disposal, the Imperium recovered many worlds lost during Old Night, and during this Great Crusade the Emperor discovered His lost gene-crafted progeny scattered throughout the galaxy. Many of the worlds encountered were brought back into the arms of Terra; either voluntarily or through the use of force. Now after centuries of endless crusade, it seemed that a new age of peace was within reach.

At Ullanor, the one threat that could truly threaten the Imperium of Man was crushed. The imposing Ork empire of Urlakk Urg was brought to its knees by the will of Mankind and the martial prowess of the Astartes. With that the greenskin hordes were brought low and the Imperium's future guaranteed. It was at Ullanor where a mass Triumph was held to celebrate all those who fought and died in over two hundred years of war and to herald the golden age to come. It was here at the Triumph's apex that the Master of Mankind declared His intent to retire to Terra to conduct a secret project that was for the betterment of humanity. To lead the Great Crusade to its victorious conclusion, the Emperor chose Horus Lupercal as His successor, elevating the First Found to the rank of Warmaster and gifted with immense powers whilst burdened with heavy responsibilities.

Horus accepted the honour, renaming his Luna Wolves the Sons of Horus as a mark of their newfound prestige. However, while many of the primarchs felt that Horus was deserving of the mantle, others felt that the likes of Sanguinius or Guilliman were more suitable for the role.

With Horus as Warmaster, the Emperor departed for Terra. Accompanying the Master of Mankind were the Iron Warriors, tasked with fortifying the Imperial Palace, with Perturabo raised to the newly created position of Emperor's Praetorian. This caused confusion amongst several of the primarchs, as Perturabo was seen as an embittered siege-master who cared little for matters of state that would undoubtedly take place on the Throneworld. None were more confused, or angered, by the announcement than Rogal Dorn of the Imperial Fists who considered his creations superior to that of the Olympian Primarch. Dorn openly criticized his father's decision yet the Emperor was unyielding on His choice for Praetorian. Later events would prove the wisdom of this decision.

Before the Emperor could return to Terra, matters over the use of sanctioned psychic powers could no longer be ignored, with tensions escalating across the nascent Imperium. As a result, the Emperor called forth a convocation on the world of Nikaea to decide on the issue of psykers within the Imperium, specifically those within the Legiones Astartes. Many held a vehement passion against psykers, such as Leman Russ, though despite this other primarchs trusted their sons with such powers, like the Death Lord and his loyal son, First Captain Calas Typhon. Many primarchs deemed psykers as foul creatures, Russ himself swore that such powers were the very witchcraft that the Great Crusade had set out to eradicate. These charges of sorcery were laid heavily against the Thousand Sons. Some, such as Dorn, wanted the Thousand Sons disbanded for their 'sin' of wanton psychic use and acquisition of dangerous knowledge.

Despite this potentially being a grave threat to his Legion, Magnus himself stayed out of the debate, though did allow his sons to speak on their own behalf. In the end, a compromise was made and enforced by the Emperor's own authority. Under the agreement, psykers were to be trained under the aegis of the Librarius. This did little to sway the Wolf King, who remained silent to Magnus' reasoning that this was for the good, and instead returned to the Great Crusade's frontlines angry and disillusioned. After the Edict of Nikaea's proclamation, the Emperor beckoned Magnus to assist Him on Terra in whatever secret works that was to be undertaken beneath the Imperial Palace. With the matter resolved, the Great Crusade continued apace. The troubles caused by the selection of Praetorian and the Edict of Nikaea were some of the first problems to arise, but far from the last.

In the years following Horus' rise to Warmaster, other events occurred between the Legions, rifts that would have dangerous repercussions in the days to come. It was upon the world of Kharaatan that Konrad Curze of the Night Lords would be enlightened to the true monstrous nature of his brother, Vulkan.

The Lord of Salamanders had always had a dark affinity towards the use of flame-based weapons, and with such weapons he laid low the human settlements of Kharataan and the Dark Eldar foe alike, while Curze could only watch on in horror. This tension reached its head with almost fatal consequence when the Lord of the Eighteenth Legion killed a Drukhari child with his own hands for little to no reason. Curze, sickened by this baseless cruelty, reported such actions to Rogal Dorn, only to find his brother likewise indifferent to Vulkan's cruelty.

"They fought against father's vision, Konrad. For that they must die, I do not think Vulkan was in any wrong for what he did," said Rogal Dorn, as though he talked to a child which only infuriated the Lord of Night further.

"He killed a child without reason! He burned the innocent without a purpose behind it! I saw him take the life of a xenos child no older than ten years old with his own hands and did so without remorse at what he was doing. Rogal, I saw men and women surrender to him, free of their psychic chains, willing and wanting to join the Imperium. And on Vulkan's orders his sons rewarded them with flame and ruin! Mark my words, there is a darkness in him. One that could mean his doom if he does not temper it," came the enraged response from Curze, disgust thick in his voice.

"You criticise our brother for his darkness. Hypocrite. You, of all us, should understand something about the darkness that resides within us all, Night Haunter," Dorn sneered the moniker.

Curze opened his mouth to respond, to defend his actions but Dorn's face was uncaring and unmoved, a face that could not be convinced that the terrible things Curze had done had been for the betterment of the Imperium. Grisly, morbid, soul-shattering duty it was, but undeniably necessary for the Great Crusade to continue and to keep the newborn empire from crumbling under its own weight. Dorn's face was shockingly similar to the look Vulkan sported when he strangled the child. It was a look born of cruelty, nothing else, for only the truly cruel could look upon the actions that had occurred without a single shred of remorse. Curze had done many things, so many terrible things, but never in carrying out his many sins did he take satisfaction in them. And that satisfaction had been on his Nocturnean brother's face and Curze could see that such dreaded satisfaction had taken root in Dorn's hearts.

"You mourn a xenos child? You mourn those too weak to stand with us? Perhaps it is you that is at fault here, Konrad. Not Vulkan. Vulkan is only all too aware of the Dark Eldar's debauchery, and as for the settlers well… what do their lives matter in the end?" came the condescending response from Dorn's lips, as if Curze was the one at fault here for the crime of compassion.

Curze said nothing, merely looking upon his brother in disappointment and for a second saw something else entirely. His head flared with pain, nose dripping blood down unto his armour and that was when he saw it. Standing before him was not a demigod clad in his resplendent finery but a lord of rot and decay, a herald of plague and death that would cause the suffering of countless billions. Curze shook his head, supressing the urge to slay his brother. The visions were getting worse, more unpredictable and violent. The Lord of Night let slip an animal snarl but turned away, knowing he needed to inform Horus of this vileness for Vulkan could not be allowed to go unpunished for his unwarranted actions. As for Rogal Dorn, the Lord of the Imperial Fists watched his brother leave, detesting what he perceived to be weakness and cowardice to do what was necessary.

Other such disputes occurred as the Great Crusade continued, as even the ever optimistic Fulgrim and recently dour Rogal Dorn almost clashed in the Cheraut System. Fulgrim was always a primarch of the people, the idea of perfection and kindness moulded into one being that longed to share his enthusiasm with all of Mankind. And so during the Compliance of Cheraut the Phoenician became disgusted with the unrelenting massacre of Cheraut's surrendered peoples, the Imperial Fist Primarch unwilling to show mercy to those he deemed beneath him.

While Fulgrim tried to bring Cheraut to a peaceful compliance with the grace and charisma that he known for, his brother saw fit to brutalise the population with tactics his sons were now becoming known for. Fulgrim watched on in shock and disgust as the Imperial Fists slaughtered the populace. Tensions reached a boiling point, almost causing the sons of Fulgrim to commit the unspeakable act of fratricidal combat against their cousins but Fulgrim was able to calm his legionnaires, and instead of battle the Emperor's Children left the Imperial Fists to their unforgivable work. The Third Primarch swore that the Emperor would hear of this and that a reckoning would soon follow. Such threats fell upon deaf ears as Rogal Dorn had already chosen his side for the coming conflict that would soon split the Imperium in two.

During these instances of conflict amongst the brotherhood of primarchs, the Warmaster's own part in the Crusade proved more fruitful, though there was still danger waiting for him. The Sons of Horus had encountered a civilisation of humans that had somehow survived the terrors of Old Night. They were known as the Interex; a highly advanced society that worked alongside several alien races in a hegemonic confederation. Their technology was more advanced than that of the Imperium in several fields, most notably in non-military ways. Their focus as a civilisation was not to wage war as the Imperium did but rather to extinguishing a force known simply as 'Kaos'.

Despite this being against the wishes of his father, Horus decided to attempt peaceful negotiations with the Interex. He was intrigued by what he saw, and hoped to bring them into the arms of the Emperor peacefully so that they may work alongside their fellow humans once more. However, some cruel twist of fate was played and the Warmaster was attacked, harmed by an assassin wielding a blade soon known to be an anathame, a blade bearing the corrupting touch of Chaos. And the wound upon the primarch was something that even the Sixteenth Legion Apothecaries could not heal.

The Warmaster fell into a fitful state, and the Sons of Horus roared at the treachery of what had occurred. A retaliation force was all but ready to exterminate the Interex, in spite of there being little proof that it was one of their own agents that tried to kill Lupercal. It took the rest of the Mournival to calm the fury of Ezekyle Abaddon, and the explanation of High Chaplain Erebus of the Word Bearers to fully explain what had happened to their gene-sire.

Erebus had been detached to the 63rd Expeditionary Fleet with a contingent of Word Bearers since the Triumph of Ullanor to fight alongside and to advise the new Warmaster, and the High Chaplain found himself worried by what he saw. The corruption of Eugen Temba, who was felled by Horus when he succumbed to some form of 'xenos-plague', reminded him of the warnings of Lorgar and Kor Phaeron of a threat that was similar to the Interex's description of 'Kaos'. With their mood calmed Erebus, alongside the representation of the Interex, explained to the Mournival what had become of their gene-sire and what had to be done to save him.

"You are telling me a concept of disorder laid our father low, Erebus?" asked Abaddon, his face scrunched in confusion, anger bubbling just beneath the surface. "Is this some form of joke?"

"Sadly no, and in a sense, Ezekyle, you are actually quite correct. These 'things', these false gods are the personification of such ideals. Mankind's fears reflected back into their faces, haunting our species for millennia, ever bringing out the worst in us, exploiting us. My lord father has been aware of such horrors for some time but my knowledge of them is fairly recent," Erebus responded, hand touching the Book of Lorgar chained to his waist.

"Who cares what their origin is," said 'Little' Horus Aximand, desperation tinging his voice. "Can you save him? Please tell me you can save him, Erebus."

Erebus looked at the faces of these lords of war and proud representatives of Mankind's strength. Their faces were wrapped with fear at the thought of losing their father and yet despite the situation, Erebus found himself calm. The Imperium needed Horus and his sons, and he would save the First Found for what was to come. Erebus' eyes burned with determination. The kind of determination that could defy even fate and the machinations of false gods. By the God-Emperor's Will and with His Blessing, Erebus would save Horus Lupercal.

"Yes," came the response from the High Chaplain. "But I shall require aid; the stubborn kind."

"You've come to right place for that, Chaplain," said Tarik Torgaddon, with a wry grin upon his face.

And with that, hope was renewed and the Mournival began the process of setting their father free.

Erebus and his Mournival cousins set out to purge the affliction that beset Horus. With the aid of the Interex, Erebus was able to discover the true nature of the Chaos blade that struck the Primarch, and what it was meant to do. It would leave Horus trapped in the clutches of what could only be described as daemons, something Erebus confirmed.

At first, Erebus privately mused that he would have to slay Horus to ensure that he did not fall to Chaos, but upon using his latent psyker abilities, Erebus sensed Horus' willpower was beyond the daemons' expectation and his dedication to his father's dream was unwavering. Inspired by the primarch's example and unwilling to leave Lupercal in the grasp of Chaos, Erebus, alongside the Mournival, began an ancient ritual to expel the corruption from the Warmaster.

In the midst of the ritual the Chaos Gods sent their firstborn son to prove his worth to them, loathed to be denied their champion. Be'lakor the Dark Master attempted to stop the ceremony and slipped through the shadows to avoid any and all confrontation until he came to the primarch's chamber where Horus Lupercal resided in a comatose state.

The Mournival left the ritual to face greater daemon, leaving it to Erebus to free their father's soul from the Fell Powers' grasp. The Colchisian Chaplain found the Warmaster's soul besieged by daemons who whispered heretical lies and misleading half-truths, Erebus reminded Horus of his work and that of his father. Erebus' words touched the heart and mind of the Sixteenth Son, reminding him that he was not fighting alone, that there would always be those to rise against tyranny and oppression.

And so Horus Lupercal's soul defeated the daemons with its pure nobility and returned to its body, and the Warmaster rose once more.

"Bastard!" roared Abaddon as he charged the nightmare-thing that had nearly interrupted Erebus' exorcism. "You bloody, motherless bastard. Get away from him! Get away from my father!"

The thing came from the shadows, horned and bat-winged, reeking of dreams lost and countless slaughtered. It attempted to antagonise the legionnaires but did not get very far as the Mournival doused the beast in bolter fire. Which did little to it unfortunately, the wounds healing as fast as they appeared. So as always it came down to blades and skill. And Abaddon would not be found wanting in that regard. The other Mournival members had been thrown about the chamber but they rose to join their brother in combat, Abaddon's stubborn defiance giving them strength to return to the fight. The warp-predator turned towards the chanting Erebus who sat in the centre of a chalk-drawn Aquila, an enraged snarl on its face and a nightmare blade clasped in its hand.

Abaddon swung his own blade and for seconds the pair duelled. The daemon was his better, Abaddon knew this. But already Garviel was on his feet and launching himself towards the monster, which looked surprised by the Mournival's sudden recovery. Tarik threw himself onto the monster's back, his single remaining arm wrapped around its throat. The beast seemed undaunted and threw the three transhumans off with ease.

"I am the Son of Chaos, Scion of the Four Kings," the gargoyle thing boasted as it drew its blade close to Abaddon's throat. "You will die here just like your father. If he will not be the chosen servant of my Ruinous Lords then he will be their plaything!"

Instead of despair on the Astartes' faces, the creature instead saw hope. Why? They should be trembling in fear for their father would now be dead and there was little they could do to stop him. Then Be'lakor could no longer hear the Chaplain's chanting and he turned to face the new threat. No matter that he had lived for millennia uncounted and had fought in wars that none now remembered and was the favourite of the Primordial Annihilator, Be'lakor turned too slow and the Talons of Horus burst through the daemon prince's chest, and he felt a demigod's breath next to his ear as the primarch dragged the daemon prince closer.

"Tell them they failed," Horus Lupercal swore, his tone that of unforgiving thunder despite how quiet the words truly were. "Tell your masters that we will never become their slaves, that we will never bow to their corruption. Tell them that this wolf and his cubs have sharp fangs indeed."

With that Horus fired the Talon's storm bolter and turned the daemon into nothing more than a wet paste as its death scream echoed through the chamber. That and the bellows of the Dark Gods denied.

With himself free of their grasp, Horus stood proud and ready to defend Mankind from this new threat. He postponed any further negotiations with the Interex but thanked them for their aid, and sent Erebus and his force of Word Bearers back to Lorgar to reveal to him this news. The Sons of Horus then set a course towards Terra, Horus hoping that his father would have the answers to the threats that now appeared from the shadows. But very little emitted from Terra, leaving only screams that pierced the veil of the churning warp. Horus prayed that this was due to his survival not being accounted for by his new foes but when he got to the safety of Sol and received reports of what was happening across the frenzied Imperium, he found the truth to be far more horrifying by far...

Treachery of The Angel Fallen

The Angel Sanguinius, Lord of Ninth Legion, had cast aside his father's teaching. He claimed that the Emperor would leave humanity stifled in the dark, unable to endure, left vulnerable to the myriad of threats that still lingered. Sanguinius declared that only through the dark knowledge that he had discovered could Mankind rise up and thrive in understanding the 'true' universe and not the false image his creator projected. The Ninth Primarch was not alone in rebelling against the Emperor. Alongside Sanguinius stood Lion El'Jonson of the Dark Angels, Ferrus Manus of the Iron Hands, and Rogal Dorn of the Imperial Fists.

The Imperium was wracked in fear of such revelations, that four Legions stood in rebellion against Emperor, and many believed that this great heresy was born of Sanguinius' anger to not have been chosen as Warmaster. Even more heart-breaking was news that the four Traitor Legions had purged their ranks of any potential loyalists on Isstvan III. It was only by chance and determination that one ship, The Sisypheum, survived and took news back to the Imperium, warning the Throne-loyal forces of this dire new threat and allowing them a chance to end the rebellion before it could spread.

"He was… my brother, my closest brother. I thought I knew him as well as I knew myself. Oh Sanguinius, I would have protected you from all harm. You needed not fear, but in the end your fear was what let them claim you. I should have known… what brother does not know the fear that consumes his own? What brother could have been so blind to another's torment?" - Extracted from the personal writings of Warmaster Horus Lupercal, Lord of the Sixteenth Legion.

Horus found himself torn by what had happened and knew who was responsible: the Forces of Chaos. Horus demanded to know why the Emperor had left His sons in the dark about these abominations and it took the cool words of Lorgar, who knew of the gods from his upbringing on Colchis, alongside the knowledge of Magnus, whom the Emperor saved from their temptations, to sway him. The Chaos Gods thrive on the fear their name creates, as well that the knowledge of them spreads their corrupting influence. The Emperor believed that in denying the gods their own existence then they would gutter out in the dark of ignorance. It was a sound theory and may have worked if not for the tenacity of the Ruinous Powers.

It was believed that Horus was to be their original avatar and champion but with the sway of Erebus and the knowledge that he knew to combat them, they turned to another. To the Dark Gods, Sanguinius was an excellent second choice to be their Champion as the Angel of Blood had close ties to many of his brothers meaning that it should be relatively easy for him to sway them into the arms of Chaos. This coupled with Sanguinius' charisma and being one of the more beloved primarchs across the Imperium made him perfect to be the one to set it aflame in the fires of civil war.

And so the Ruinous Powers fanned the embers of fear in Sanguinius' heart, the fear of what his angelic wings meant and how he, a symbol of faith, existed in what the Emperor claimed to be a godless universe. This fear coupled with the flaw in his own genetic line drove Sanguinius to desperate madness in his attempts to justify his own existence. The forbidden knowledge he found turned him into the Champion of the Primordial Annihilator, the Arch-Traitor of the Imperium, the Angel Fallen. And thus Sanguinius became the Fell Gods' chosen warlord to usurp the throne of the Master of Mankind and become emperor of an Imperium Chaotica.

Just as Horus arrived to the Throneworld, learning of the Isstvan Atrocity and the warp storms affecting the galaxy in an intensity not seen since Old Night, a new fleet commanded by Ahzek Ahriman arrived to the Sol System, bearing despairing news. This fleet was battle-scarred, carrying the survivors of Prospero, victims of Leman Russ' slaughter as it seemed the Wolf King had decided to settle the debt between him and the sons of Magnus. He claimed that the planet was a black mark on the Imperium that had to be purged, but instead of being thanked, Leman Russ was cursed and labelled traitor. The Emperor himself was aghast at what His Sixth Son had done, while Magnus could only swear vengeance through his own tears upon Russ and his untamed Wolves for what they had done to Magnus' homeworld and people. Horus, who was certain that the situation could be dealt with swiftly, now began to realize the true extent of the corruption in the Imperium as well as how insidious the Gods of Chaos were.

It was at this time Perturabo had returned from his own trial of a full-fledged uprising on Olympia. The world has become influenced by a strange affliction that Perturabo could only assume was of xenos origin. He returned to his homeworld to save it from this infection, and was forced to bathe half of it in fire to cleanse it, taking the lives of many innocent. Head hung in shame, Perturabo presented himself to the Emperor for judgment but the Emperor absolved Perturabo of this crime for He knew the true origin of the affliction and informed His Praetorian of who was behind it.

With his temperament enraged and desiring revenge upon these powers, Perturabo swore to see that all who betrayed or attacked the Imperium would die without mercy. But as a result of the rebellion on Olympia, Perturabo had just missed the opportunity to join the Retribution Armada that had departed for the Isstvan System. Though initially frustrated, this would turn out to be a blessing in disguise and having the Praetorian on Terra would have far-reaching consequences in the years to come.

Seven Legions arrived to Isstvan to put an end to Sanguinius' heresy. First came the full might of the Death Guard, Mortarion eager to quash all who would defy his father. Alpharius commanded the lion's share of the Twentieth Legion, committed to preserving the Emperor's dream. Next came the Ultramarines, and their presence bolstered the Armada's morale because with XIII and the many legionnaires within it how could the traitors defy them?

The presence of Vulkan and Corax was an unwelcome one as their Legions held dark reputations, one of unstable gene-seed and the other the brutality of fire. But such faults were cast aside due to the situation and so they were welcomed for the battle to come. Fulgrim's sons and the White Scars were next to appear and some feared the enmity between these two Legions would cause a tension in the ranks, but it seemed the two primarchs had managed to quash such attitudes, despite the smirk which seemed present on Jaghatai Khan's face during the war council.

Confusion lingered among the Imperials as the traitors' void-fleets had somehow vanished, nowhere to be seen, but it was known that the rebel legionnaires themselves were entrenched on Isstvan V. Wary of a trap, the Throne-loyal forces decided that three Legions would be the ones to secure a landing zone for the others to follow. And so it was Mortarion, Alpharius and Fulgrim that would form the first wave to make planetfall. Mortarion volunteered due to the kind of trench-breaking warfare that was to be expected suited his Legion's tactics; Alpharius for his ability to exploit any weaknesses in the traitor lines that would cause confusion amongst the traitors; and Fulgrim who longed long to kill Sanguinius for his betrayal, for once they were as close as brothers could be.

So the three demigods of war made planetfall with their legionnaires to punish their wayward kin and the skies of Isstvan V burned in their wake as drop-pods and dropships filled with warriors burning with righteous indignation descended to the black sands of the Urgall Depression. Many Astartes died before they ever reached the ground, their drop-pods and dropships destroyed by traitor anti-aircraft cannons. When the three Legions landed, they fought against their treacherous kin and the true extent of their brothers' corruption made itself known. Those who sided with Sanguinius had become something truly corrupt, gone was the image that the Emperor had for His sons, replaced instead by the worst nightmares Mankind had ever dreamt.

The sons of Ferrus Manus fought like mad berserkers, their own inherent Medusan rage made more potent by the Blood God's influence, driving the Iron Hands to slaughter with abandon. The Iron Tenth fought as the vanguard for this heresy, revelling in all the blood spilt and the skulls collected as trophies, uncaring of their own casualties. Ferrus Manus fought on the front-lines alongside his sons, challenging Fulgrim to face him. The Gorgon hefted Forgebreaker, a gift given long ago by his once most favoured brother, and his hands of iron ran hot with blood.

The Dark Angels had once been the paragons of noble chivalry, but now killed with a lover's pleasure. Each kill gave them not the accomplished sense of duty but rather the relish of experiencing the murder of their own cousins. Each death dealt was a thrill; each wound taken was a pleasure-filled luxury enhanced by the Dark Prince's caress. Sighs left scarred lips as their own limbs were blown off by bolter fire or bodies bisected by power swords, their maddened gleeful laughter echoing over the battlefield. Such was their corruption.

Rogal Dorn and his sons had transformed from once stoic and honourable warriors to now being bloated and malformed, acting as carriers of many foul sicknesses and plagues. Rot had taken many of them, foul ichor mingling with their blood and giving them endurance to pain never before imagined. Rogal Dorn's personal chainsword Storm's Teeth had become corroded with rust and clotted with disease-ridden waste yet the weapon still worked and reaped a heavy toll against loyalist Space Marines.

But worst of all were the Blood Angels. Gone were their nobility and angelic beauty, gone were the warriors that once were considered the equals of the beloved XVI. Now they were daubed in vigils of Ruin, screaming prayers to the Primordial Annihilator as they killed. Alongside them fought monsters, wild-eyed beasts, which to the horror of the loyalists were revealed to be Blood Angels themselves, or at least had been before allowing daemons to dwell in their flesh. Many had wings burst from their back, in cruel imitation of the flaw that drove their primogenitor mad, while their hunger for blood rivalled that of the Iron Hands.

For hours the two forces faced each other and in that time, the loyalists were able to establish a landing zone for the second wave, though they would bitterly regret that by day's end. The traitors' heavy artillery and anti-aircraft emplacements were eventually destroyed. Fulgrim informed his brothers waiting in orbit and soon enough the White Scars, Salamanders, Ultramarines and Raven Guard deployed to the landing zones, fortifying them upon arrival. The Death Guard, Alpha Legion and Emperor's Children, weary after a long day of heavy fighting and in need of reinforcement and resupply, withdrew to the landing zones to rendezvous with their reinforcements.

What should have been the death-knell of the rebellion instead turned into one of its greatest victories as the White Scars, Salamanders, Ultramarines and Raven Guard opened fire upon their former allies, slaughtering them with ease, killing thousands of legionnaires within minutes.

Fulgrim ran, dirt clogging his helm, forcing him to discard it. It fell to the black earth with a thud. His own transhuman muscles burned with effort and pain. The pain pulsed from the wound he had acquired from his duel with Ferrus and despite his premiere skill with a blade, Fulgrim had almost died facing his blood-crazed brother. The bastard almost took Fulgrim's skull with the weapon Fulgrim gave him all those years ago beneath the Urals. But the worst pain was that of his sons fighting their cousins. It was something that they should never have had to do.

Beyond the hill he could see the Ultramarines, those blue-clad cowards who were doing little to defend him and his sons from the fire of the Blood Angels.

"This is Fulgrim of the Emperor's Children, fire upon the Blood Angels! That is a direct order! Fire upon the-"

Fulgrim dived for cover, saved by his own reflexes, as the Ultramarines did open fire only it was upon him and his sons.

The subtle gambit paid off and the traitors revealed their true allegiance as the opening salvoes halved the Emperor-sworn forces, though the loyalists were able to kill one Traitor Primarch in return. Jaghatai Khan was slain in the killing fields by Mortarion, before the Warhawk could lay low the Phoenician. Still this mattered little as they were nonetheless overwhelmed, and the loss of one rebel Legion sent into disarray did not stem the tide of traitors eager to spill blood. And the victory Mortarion achieved was short-lived as Rogal Dorn cornered his Barbaran brother and slew the Death Lord who was wounded during his fight with Jaghatai. The Death Guard did not lose cohesion like the White Scars did upon the death of their gene-sire, thanks purely to First Captain Calas Typhon who rallied his brothers, not allowing their grief and anger to override their senses.

And in high orbit, the traitors emerged from their hidden recesses within the warp, safe for they were chosen by the gods, and with the aid of their recently revealed allies they were able to tear apart the Imperial fleet above. It was only by great sacrifice and the killing power of the Terminus Est alongside the chaotic confusion among the White Scars caused by their primarch's death did the loyalists escape, and send word back to the Throneworld of the treachery that had happened. The battle that took place on Isstvan V would forever be known as the Dropsite Massacre. Sanguinius' master plan had seen three Imperial Legions nearly wiped out, one Loyalist Primarch confirmed dead, while rumours of Alpharius being killed as well were whispered but never proven in the battle's immediate aftermath, and over two hundred thousand loyalist legionnaires were slain in a single day.

Horus quickly retaliated, ordering the World Eaters and Word Bearers to invade and cripple the Realm of Ultramar. The Warmaster knew that Guilliman's Five Hundred Worlds would in time become a fortified holdfast of traitor activity and would become their greatest source of weapons, munitions and manpower if left unmolested. Lorgar had predicted the order and had amassed his Word Bearers, alongside three recently constructed Abyss-class kingships forged in secret with the Mechanicum. The Warmaster planned for the two very different primarchs to offset each other weaknesses and complement their strengths. It was hoped that Angron would contain Lorgar's zeal while the Urizen would calm Lord of the Red Sands' infamous temper and battle-thirst.

Unfortunately for the Imperium, Sanguinius and Guilliman had predicted such an attack, and the bulk of the Ultramarines had been redeployed to Ultramar to prevent its destruction. Guilliman and his Ultramarines were able to halt the XII and XVII, though at great cost. Guilliman sacrificed dozens of worlds within his domain to form the Ruinstorm that encompassed Ultramar, allowing none but those sworn to Sanguinius to arrive and depart as they please. The act of sacrificing untold billions of citizens he was sworn to protect began to drive the Battle-King of Macragge to grief-ridden despair, his guilty conscience combating with a hungry ambition that was being fuelled by the Dark Powers.

As a result of the Ruinstorm, the Word Bearers and World Eaters were trapped within Ultramar, but so too were the bulk of the XIII who remained to prevent their Realm's immense industrial base from being destroyed by the loyalists. Despite the assault of two Loyalist Legions, supplies nonetheless continued to be delivered to the Arch-Traitor and his armies for the entirety of the Heresy. Though Sanguinius' supply and logistics were secured, and two Throne-loyal Legions isolated from the rest of the Imperium, the Arch-Betrayer lost his greatest asset: Guilliman and most of the XIII. Only a large contingent of Ultramarines commanded by First Master Marius Gage fought alongside the Angel Fallen for the entirety of the Sanguinary Heresy.

The Path to the Throneworld

Three Legions shattered at Isstvan, the Thousand Sons' homeworld razed to the ground and their Legion reduced to a fraction of its former size, and roughly half of the Imperial Army and Mechanicum had forsworn their oaths to the Emperor in favour of Sanguinius. Mars itself had fallen victim to Sanguinius' madness, with the Red Planet split between those who believed the Emperor to be the Omnissiah and those who did not. Those hereteks who dabbled in various extremes of tech-heresy formed the Dark Mechanicum led by the brilliantly enigmatic but highly dangerous Archmagos Belisarius Cawl. The Angel Fallen looked to be on the cusp of victory. All the Arch-Betrayer had to do was marshal those loyal to him and make way to Terra and override Perturabo's incomplete defences.

But it is said that the greatest enemy of Chaos is Chaos itself and this was proven true during the Heresy. The Traitor Legions, especially those chosen to serve a particular facet of the Primordial Annihilator, pursued their own objectives and desires, only occasionally being commanded by their titular leader Sanguinius. Their contradictory motivations caused the rebellion's momentum to slow to a crawl for much of the civil war, allowing Perturabo to fortify the Sol System to resist the encroaching storm.

The Iron Hands attacked any and all Imperial forces that they came across, reaping a heavy tally on loyalists across the galaxy. The Imperial Fists, seeking to prove themselves against their hated rivals, attacked Iron Warrior Fortress Worlds one after another, using their putrid gifts and near-unrivalled mastery of siege warfare to overrun Imperial defences, though the VII suffered heavy casualties as a result. The Lion's get became obsessed with attacking densely populated worlds, charming them with their falsehood of honour before taking their lives in ever more decadent ways.

This continued until the Dark Angels invaded the Webway to hunt down the Eldar for their patron god. Corvus Corax led his sons back to their homeworld, taken there by the whispers of the God of Change, whose lies had enticed Corax and convinced him that the path to immortality and correcting his gene-line's rampant mutation resided deep in the mines of Deliverance. Vulkan simply burned world after world, but those closest to the Lord of Drakes could tell he was troubled, born of the confusion of what he was, as well as how that would affect his own desires to otherworldly ascension. The White Scars, still reeling from their primarch's death on Isstvan, were redirected by Sanguinius to hunt down the surviving elements of the Shattered Legions, specifically the Death Guard in retribution for Mortarion's slaying of Jaghatai. Though this prevented a majority of the V from fighting alongside Sanguinius during much of the Heresy, the Arch-Traitor deemed it worth the cost as the White Scars prevented the three Legions shattered at Isstvan from uniting and reforming, as well as limiting the threat they posed to the traitors' principal fleets.

As for Leman Russ, after the Burning of Prospero and declaration of allegiance to Sanguinius, the Wolf King departed for the Great Storm located in the galactic north, soon to be known forevermore as the Eye of Terror. He was accompanied by his Thirteenth Great Company, veterans of hundreds of campaigns and utterly loyal to their king. It has been speculated that Russ did so to accumulate the power necessary to confront and kill Magnus the Red in their inevitable confrontation that would take place during the Heresy's last battle. And Russ would acquire these powers, at great cost. Prior to his departure, the Sixth Primarch ordered his sons to spread across the galaxy in their great companies and ensure the Arch-Betrayer reached Terra. As a result the Space Wolves were one of the Angel Fallen's more dependable allies, though none could compete with the Ultramarines led by Marius Gage who were able to resist the dark desires that tempted them. The Ultramarines' First Master followed Sanguinius' orders without hesitation and began to view the Ninth Primarch as a sort of surrogate father in Guilliman's absence.

Soon enough the Dark Angels returned from their foray into the Webway, changed and corrupted far more than what they had been on Isstvan V. Lion El'Jonson had ascended to the rank of Daemon Prince of Slaanesh. After his ascension and return to real-space, the Lion sailed to his homeworld of Caliban, eager to tear it asunder. Though for what reason this is unknown to many in the Inquisition's learned circles, even to this day. Still, the Lion's ascension to daemonhood showed the true level of the traitors' deplorable nature that was quickly taking root throughout the Fallen Legions.

Though the Imperium reeled from the colossal military disaster that was the Dropsite Massacre, this did not prevent some from taking the fight to the traitors. The Death Guard, driven to avenge their father, continuously assaulted the Arch-Traitor's exposed flanks, threatening to bisect the traitors' forces in two, but after Sanguinius unleashed the frenzied White Scars upon them, the XIV were unable to continue their pincer movements but would go on to hold the attention of a majority of the Fifth Legion's brotherhoods for the remainder of the Heresy.

The Alpha Legion, bloodied but not crippled, initiated galactic-wide sabotage, infiltration and guerrilla warfare against the traitors, assassinating rebel commanders and plaguing traitor logistics, as well as instigating mass revolts amongst the Traitor Imperial Army. Only a third of the Emperor's Children survived Isstvan V, but nonetheless harassed and bloodied the traitors every step of the way during their drive towards Terra, though rarely did so as a united force, preferring small, highly mobile strike forces.

Though every Legion loyal to the Emperor contributed in some way to slowing down the Arch-Traitor's offensives, it was the scions of Konrad Curze who most openly stalled Sanguinius' offensives. The Night Lords had assembled in full force to take part in the Retribution Armada but had answered the call just too late to take part in what would become the Dropsite Massacre. As the Shattered Legions of the Death Guard, Alpha Legion, and Emperor's Children fractured, largely becoming disorganized and isolated, it was the Night Lords who engaged the Blood Angels and their allies head on, carving deep wounds into Sanguinius' armies and fleets. Though Sanguinius won most of the engagements against the Night Haunter, Curze cared little, his only goal was to buy Terra time to prepare for the onslaught to come. And buy time he did. Imperial analysts hypothesise that the actions the Lord of Night and his sons carried out gave Horus, Magnus and Perturabo years to fortify the Throneworld. Entire Traitor Space Marine companies fell to the talons of the VIII, countless Army regiments butchered and their corpses put on display to successfully unnerve their comrades.

But as the Heresy drudged onwards, the VIII and other Imperial forces were pushed ever backwards towards the Segmentum Solar. To make matters worse, Leman Russ had returned from the Eye of Terror, empowered by whatever fell gods resided there, and recalled his sons to his side once more. Further detrimental to the Imperial cause, was the arrival of Roboute Guilliman from the Ruinstorm-enclosed Five Hundred Worlds. The Lord of Ultramar had successfully prevented the Alpha Legion from freeing the XII and XVII, killing Alpharius in personal combat on the world of Eskrador and this time the death of the Last Primarch was no rumour but fact, the body of Alpharius positively identified and paraded through the Honour of Macragge as a trophy. With the Space Wolves and Ultramarines now whole once more and bolstering his main fleets, the Arch-Traitor began the final push into the Imperium's heartland. Leman Russ defeated the Night Lords at Yarant, shattering them and preventing their reinforcement of Terra, while Sanguinius himself led the massive campaign against the loyalists defending Beta-Garmon.

Despite years of preparation, Beta-Garmon soon fell to the IX and XIII after months of harrowing battle. The defenders fought to the last man, trying to turn Sanguinius' tactical victory into a costly strategic defeat, but the Angel Fallen overcame the defenders and their tactics, securing the world considered the Gateway to Sol after months of combat. With the twin victories of Yarant and Beta-Garmon, Sanguinius called for his allies to gather for the assault on Sol. Soon enough the Nine Traitor Legions were assembled, ready to cast down the Emperor from His Throne.

Ever since news of the Dropsite Massacre reached Terra, Horus, Magnus and Perturabo knew that the situation was dire. All that could be done was to prepare for what was to come and called for their sons to aid them in this endeavour. Countless millions of Terran mortals were called to honour their oaths to the Emperor, drafted into the Imperial Army. Mars, torn apart by the civil war, had finally been brought to heel by Iron Warriors led by Triarchs Kydomor Forrix and Erasmus Golg, though the price paid had been very high.

To make matters worse, the Dark Mechanicum de facto leader Belisarius Cawl had escaped the Martian Schism's final battles, joining forces with Sanguinius in Beta-Garmon and revealing to the Ninth Primarch terrible weapons that would reap havoc across Terra during the Heresy's final months. A flicker of hope revealed itself prior to the traitors' arrival to Sol in the form of the Alpha Legion, led by their primarch. The 'confirmed' report of Alpharius' demise on Eskrador now revealed itself to be an Ultramarine deception. The Twentieth Primarch led the remnants of his Legion to Terra, reinforcing the Throneworld as much as they were able in what would become Mankind's darkest hour.

The Siege of Terra

And so it was after several long years since the Heresy's violent birth at Isstvan, that the civil war reached its final stage. The Nine Traitor Legions arrived in all their horrid might, ready to seize the empire they had helped build and then subsequently torn apart in their pursuit of power.

The Traitor Legions and their allies broke through the many defences erected by Praetorian Perturabo. The augur relays of Pluto, the Jovian Moon shipyards, the fortress-littered Asteroid Belt: all fell to the Arch-Betrayer and his hordes. After thirty days of system-wide void-warfare and conquering the various Solar Colonies, the rebels had finally arrived to Terra. Hundreds of billions of men and women looked up into the heavens and saw only death encroaching on them.

Luna fell to the traitors' assault and soon enough the Iron Hands and Blood Angels captured the Lion's Gate and Eternity Wall Spaceports respectively, allowing the traitors to land en masse on the Throneworld's surface. The Siege of Terra had finally begun.

The Iron Hands charged forward against the walls of the Imperial Palace, uncaring of those lost while behind them the Imperial Fists brought with them the many foul devices of Rogal Dorn, including the Sky Fortress which rained steel and fire upon the loyalists. The Sky Fortress, built specifically by Dorn to break through the orbital defences of Terra, ravaged huge swathes of Mankind's Cradle. It was thanks only to the Legio Mortis, redeployed to Terra following the successful conclusion of the Schism of Mars, was the foul thing brought down. As it fell it collapsed upon several Chapters of the Ultramarines, burning them in the fires of judgment. However, this did little to stem the flood of traitors and daemons. They loyalists were outnumbered, their forces thinly stretched throughout the Imperial Palace, and the ever firing barrage of high-explosive artillery continued for weeks on end, damaging Perturabo's defences. Every day the traitors tightened the noose around the loyalists' necks. The Warmaster's peerless leadership, the Praetorian's masterfully constructed defensive works, the Crimson King's psychic prowess, and the Hydra Lord's forays into the traitors' weak spots staved off Imperial collapse.

But not all was going well for the traitors. Casualties were skyrocketing, the Dark Angels had left the siege of the Palace to sate their hedonistic hungers against Terra's populace, and far more prevented the traitors from seizing victory. Sanguinius called upon more and more of the daemonic to aid him, their numbers swarming loyalist lines. As the traitors reached the Eternity Gate and began to assail this last great formidable bulwark, word reached the Angel Fallen that caused the Arch-Betrayer to grow desperate.

Three Loyal Legions had emerged from the warp, eager to spill traitor blood. The Emperor's Children, led by their sorrowed gene-sire, had recently united their Legion in full for the first time since the Dropsite Massacre and were going to make a last suicidal charge against the traitors to help alleviate pressure on Terra's defenders. But luckily for the Imperium, the Emperor's Children were joined by the recently arrived World Eaters and Word Bearers, fresh from their wars in the Ruinstorm which they had mysteriously escaped from. Though all three Legions were greatly reduced and bloodied, none hesitated in heading towards the Throneworld to save the Emperor.

"Traitors! Seeking my father's blood!? Vengeance has come to spill yours in return. Like the high-riders of old, they seek to shackle and oppress Mankind! And we will gladly meet them in battle and tear them limb from limb. Warriors of the Twelfth, Seventeenth and Third Legions, prepare for battle!" - Transmission from Angron, Primarch of the World Eaters, just before planetfall.

The loyalists attacked the traitors' poorly defended rear, cutting through the rebel armada in their drive to reach Terra's surface. The traitor lines buckled against the assault of the three Legions, each of them having honed their ability for combat through either the Ruinstorm or the hordes of daemons sent to stall them. The three Loyalist Legions quickly entered Terran orbit and rapidly deployed their forces planet side. The Ultramarines suffered the most casualties from this assault as many a Word Bearer or World Eater longed to gain vengeance for the Ruinstorm and the brothers lost to the madness of daemons.

Guilliman himself seemed almost lost, as if in a dream. The Thirteenth Son could not seem to organise his sons as he once did. Many believed that the corruption of the Ruinstorm and the damnable acts the Lord of Ultramar had carried out since Isstvan took him of his wits, while others believed that upon the gates of Terra he realised the trust cost of his heresy. It mattered little in the end when Fulgrim confronted Guilliman in the ruins of the Outer Palace.

Guilliman watched everything burn, he watched the great Sky Fortress of Rogal fall to the earth, killing thousands of his sons within minutes. Across the vox he could hear their death cries. But it didn't matter for this was all for the glory of Sanguinius and the Chaos Gods. Only through blood could they ascend. Only through sacrifice could true power be attained. If so, then why did nothing make sense? Why did he feel so lost? He remembered his worlds in the Ruinstorm, the Five Hundred Worlds of Ultramar. Once pristine and the model of an Imperial world, now covered in warp-fire and ruled by the damned and the daemonic. He remembered the look of rage on Angron's face and the judgment on Lorgar's as well as his… pity.

It didn't matter. All of this was for the good, all for Mankind's betterment. Father was a tyrant that needed to be dethroned. It was all for -

"Roboute!" a voice yelled, breaking Roboute from his thoughts. The sound of war and a world screaming in torment carried upon the wind, as did the smell of death and despair.

He turned to see Fulgrim, Lord of Chemos, looking upon him with a face of pale perfect granite. Guilliman had been judged by Fulgrim and in his black heart he knew that only one of them would walk away from this.

"Was it all worth it?" the Phoenician asked, his voice soft as he gestured to the carnage and madness that surrounded them. "Was damning yourself all worth this?"

In response Guilliman ignited the Fists of Ultramar. "One way or another we'll get what is owed."

"Will that quieten the screams, brother?" Fulgrim asked, his voice as gentle as the mystical seas of his homeworld.

Guilliman said nothing but let loose a wordless cry of rage on his lips, one that would have shamed Angron.

And the battle between primarchs began.

The fate of humanity hung in the balance as primarchs duelled across Terra. Fulgrim cornered Guilliman, Alpharius hunted down the Lion, and Magnus, wishing to seek revenge on Leman Russ for the Wolf King's genocide of Prospero, readied his elite guard to attack the Lord of the Rout, but Horus Lupercal prevented his brother from doing so, citing that the Crimson King needed to stay and preserve the psychic barriers that defended the Inner Palace. Magnus relented, and in his place sallied forth the Warmaster and his sons.

The Warmaster met the Executioner, and after a close battle that drew the eyes of all present, Horus struck down his brother with the Emperor-forged power mace Worldbreaker, destroying Russ' great spear and sending Russ into a deep coma. Before the killing blow could be delivered, word reached Horus of a brother of his being endanger. The Warmaster quickly arrived to save Alpharius from Lion El'Jonson. The Warmaster defeated the First Primarch using his Talons, though they were broken upon a deep wound across the Lion's chest. Lion El'Jonson, a Daemon-Primarch, could never truly die but was banished to the Eye of Terror, though his temporary death caused the Dark Angels to fall upon the ground, writhing with painful ecstasy at the sensation their primogenitor's psychic death-scream brought them. The Sons of Horus and Alpha Legion began to execute their former comrades, ending their treachery as the Angels of Caliban gasped with pleasure as they died.

Meanwhile the duel between the Third and Thirteenth Primarchs continued, with Guilliman bellowing wordless rage while the Phoenician fought on in silence. The two battled for hours with no end in sight, but it was only due to the heroic sacrifice of Lucius, a champion of the Emperor's Children, whose distraction allowed Fulgrim to deliver the killing blow, forever ending Roboute Guilliman. Fulgrim, body covered in dozens of wounds, collapsed from exhaustion and blood loss, his Astartes carrying him to safety. Though the Phoenician would live, he was unable to partake in the end, much to his sorrow. The Ultramarines began to fracture as word of their primarch's death spread. Only First Master Marius Gage prevented the XIII from completely routing.

With Lion El'Jonson banished and Roboute Guilliman dead, the tide threatened to turn. The Arch-Traitor gathered Vulkan, Rogal Dorn and Ferrus Manus to his side and the power of four demigods broke through the loyalist defences leading into the Sanctum Imperialis. Rogal Dorn combated Perturabo at the broken Eternity Gate, while Sanguinius led Vulkan and Ferrus Manus into the Throne Room to kill the Emperor. The only loyal son defending the Master of Mankind was Magnus the Red.

The Fifteenth Primarch, weakened after months of using his psychic powers for defensive purposes, nonetheless was a being made for war by the Emperor Himself and a result the Crimson King unleashed a torrent of warp-energy against the traitors. Vulkan was hurt, but the Lord of Drakes instantly healed, while Sanguinius' gods-given protection prevented harm and Ferrus Manus' was able to wade through the warp-fire and lightning with ease due to the Blood God's favour. Seeing his Immaterial powers being ineffective, Magnus readied his blade as the three Traitor Primarchs approached him. Magnus and the Legio Custodes were the only thing protecting the Emperor and they would fight to preserve Him.

Horus had heard panicked vox reports of the four Traitor Primarchs attacking the Eternity Gate and rushed over. Awaiting him were Angron and Lorgar. The three hurried to the Throne Room, unable to take part in the titanic engagement between Perturabo and Dorn who still battled without pause. The three primarchs arrived to what could only be described as a slaughterhouse. Almost all of the Companions, the elite three hundred Custodes who protected the Emperor's person directly, lay dead before the Throne Room's doors while Magnus' body lay broken on the floor, Ferrus Manus poised to end the Crimson King.

With a roar, Angron rushed the Tenth Primarch with his chainaxes while Lorgar muttered prayers to his father as he approached Vulkan. With the opening provided, Horus hurried to save his vulnerable father from Sanguinius, before all was lost. Horus at first begged Sanguinius to turn back from his treachery, to repent and seek forgiveness but the Angel of Blood was too far gone, the Chaos Gods having warped his mind and corrupted his soul.

Hardening his resolve, the Warmaster fought the Arch-Betrayer. The Emperor, however, was unable to intervene for it was only due to His god-like willpower upon the Golden Throne that the daemon hordes had not entered through a Webway gate on Terra itself and swarmed the entire world. He could only watch on from His throne as His sons fought at the Throne Room's entrance.

In orbit the arrival of the three Loyal Legions had stalemated the fight for void supremacy while on the ground the tides of battle shifted with every passing minute. Both sides knew the outcome of the entire war depended on what was happening in the Throne Room.

Together the two closest sons of the Emperor fought, Horus threw accusation upon accusation at the Angel's feet. But Sanguinius was unmoved and uncaring of Horus' words, instead calling the First Found a coward for the path that he took. Horus could not stop Sanguinius, as he was weak and weary from fighting Russ and the Lion, and his Talons had broken upon the First Primarch, and soon the Angel Fallen began to push the Warmaster back. Despite dealing several wounds to Sanguinius, it was the Angel Fallen who emerged victorious, his Blade Encarmine piercing Horus' chest, rupturing both of the Warmaster's hearts. For further mockery Sanguinius threw the body of his once beloved brother out into the corridor for the surviving Astartes and Custodes to see Horus Lupercal's corpse. Word quickly spread, Sanguinius hoping to disrupt loyalist morale.

With that the Emperor decreed He could not standby any longer and rose from His Golden Throne, Malcador voluntarily placing Himself onto the archeotech, taking the Throne's burden willingly. And now after years of gruesome civil war with trillions dead and whole worlds burned to a cinder, the father now faced His wayward son. The Blade Encarmine clashed with the Emperor's fiery golden blade. And though a psyker of unparalleled might, the Emperor had grown exhausted after years holding the daemons in the Webway at bay, and found Himself threatened by the might of Sanguinius and the Chaos energies that swelled within him as the two engaged in their climatic battle. The Emperor realised He could not beat Sanguinius, for He was weakened by the Throne's exacting burden. Sanguinius was prepared to end his father's regime when Magnus the Red, who had managed to recover some, made his way to the Throne Room's doorway and sent a last burst of psychic energy to stun the Arch-Betrayer.

The Emperor used this distraction to kill the Angel Fallen, and in that moment it is said Sanguinius realised how far he had truly fallen. To add further insult the sheer power of the blow cast Sanguinius into the Palace corridor to lie beside the body of Horus. With the death of their gene-sire, the Blood Angels were left in disarray, unable to do anything but flee with their father's corpse, as well as the body of Horus on the orders of the traitor Emperor's Children Chief Apothecary Fabius Bile. The Ninth Legion fled Terra, broken and disheartened. With that the traitors fled the Throneworld in droves, following the Blood Angels' example and suffering horrendous casualties in the mad dash to escape the vengeful loyalists. The losses suffered during the hectic retreat from Terra earned the Blood Angels the enmity of the other Traitor Legions.

Though there was still tragedy to be had as Malcador had been reduced to a pile of dust from the strain of directing the Golden Throne and the Astronomican in the Emperor's absence. The Emperor, now mortally wounded, was adamant that He Himself to be permanently interred onto the arcane machine. And so Magnus and Perturabo followed their father's wishes and interned Him on the Golden Throne, sustained by its advanced technology and the daily sacrifice of a thousand psykers.

A Dark Millennium

A new order was now needed following the death of Horus and the Emperor's internment upon the Golden Throne as there was much to do in order to fix the ruin left in the Sanguinary Heresy's wake. The remaining Loyalist Primarchs and other surviving Imperial leaders banded together to prevent the Imperium from collapsing. The Mournival took up their father's leadership of the XVI and vowed to recover his corpse from the grasp of Fabius Bile and his allies in the Traitor Legions. But such a crusade had to be postponed as the Imperium needed rebuilding before there could be vengeance.

The first priority was to hunt down and push the Traitor Legions into the Eye of Terror as well as reclaim and restore all the Imperium lost during the rebellion. So followed the Great Scouring where the Loyalist Legions and other Imperial forces pushed back against the darkness covering much of the galaxy. It would take years, with battles and campaigns rivaling those undertaken during the Heresy. Notable campaigns included the actions taken against the Traitor Legion homeworlds, except for the Tri-Worlds of Baal which had been relocated to the Eye of Terror, the Liberation of Beta-Garmon, the Cleansing of Morabon, the War of Abominates, and the First Cadian War.

Though many great victories were secured, the Imperials suffered grave defeats in the restoration of their empire. Fulgrim, Primarch of the Emperor's Children, disappeared during the War of Abominates. In the campaign against the Iron Hands and rogue Fabius Bile, the last known act of the Phoenician was him duelling the Blood Gorgon to allow his battered Legion to escape from the trap they found themselves in. Furthermore, the loss of Konrad Curze to a Chaos Assassin was another devastating blow to a weakened Imperium, but the Night Haunter's selfless sacrifice saved his Legion from the dark path it had begun to embark on since Sanguinius raised the flag of rebellion.

Their sire's death saw to a spiritual change, the VIII developing stringent efforts to create a compromise between their benevolent humane compassion and their darker terror-causing tendencies, using the strengths of both while avoiding potential weakness or corruption. Still, the loss of Curze was mourned across the Imperium but his sons returned to their rightful place as enforcers of the Lex Imperialis, a position they have held for over ten millennia. The loss of two more Loyalist Primarchs was a catastrophic blow to the Imperium, but one it weathered under the leadership of those that remained.

Finally, after years of civil war and incalculable strife, the Traitor Legions had been ousted from their territories in real-space and the borders of the Imperium restored. The Great Scouring was over. The Age of Imperium could now begin.

It would take centuries more, but the Imperium stabilised itself and began the process of rebuilding. The Loyalist Legions recovered and eventually expanded far beyond their pre-Heresy strength. Reforms were carried out, new organisations founded, and the newer more unknown and less enlightened era began. Without the Emperor to do so Himself, the responsibility of ruling and guiding the Imperium fell upon the High Lords of Terra, successors to the Council of Terra. As the destructive fires of the Heresy cooled, two new organisations emerged: the Inquisition and the Ecclesiarchy. The Imperial Legions accepted the establishment of the Inquisition without much issue, for the Emperor and His trusted Regent had seen to its initial creation in the dark days of the Heresy, while the Imperial Church on the other hand became a point of contention.

Violent wars of faith swept through the recovering Imperium in the decades after the Scouring, different sects of the Imperial Faith vying for control. It wasn't until Lorgar Aurelian unified and codified the Imperial Creed into the Adeptus Ministorum, instituting his Word Bearers as the Ecclesiarchy's Chamber Militant, that these detrimental wars ceased.

Many who believed in the God-Emperor, and even those who did not, questioned why Lorgar Aurelian did not accept the mantle of Ecclesiarch, for it was Lorgar who had written many of the Church's religious texts and had been the effective founder of the Imperial Faith since his discovery on Colchis centuries ago, but the Urizen refused the office, saying that he and his sons could not effectively guide the Faith whilst simultaneously defending it. The Seventeenth Primarch argued that it should fall to mortal men and women to guide the species' spiritual path and not the primarchs and transhuman Astartes who had been necessarily removed from base Mankind to better protect it. Therefore the first Ecclesiarch became Cyrene Valantion, the Blessed Lady of Monarchia, who had become Confessor of the Word Bearers during the Great Crusade's final decades and acted as a spiritual beacon during Shadow Crusade, helping legionnaires and mortal crew alike withstand the Ruinstorm's many horrors.

In the Eye of Terror, the Dark Angels, White Scars, Space Wolves, Imperial Fists, Blood Angels, Iron Hands, Salamanders and Raven Guard battle each other within the Eye, too cruel to truly put aside their divisions and conquer the Imperium. Meanwhile, the Daemon-Primarchs play the Great Game of Chaos, largely unconcerned with the affairs of their sons and other mortal beings.

The Dark Angels reside on the Daemon World of Sycorax, a planet in mimicry of the Caliban of old but one corrupted by Slaanesh's hedonistic caress. Courts of false nobility cover the Daemon World, where the largest and greatest house the First Primarch, who bides his time until the wound dealt to him by Luther and worsened by Horus has healed. While he recovers, the Lord of the First Legion sends out his warband-companies to hunt down the Unforgiven and to carry banners bearing the Sigil of the Dark Prince and the Winged Sword of the Legion into the many wars waged against the Imperium and their fellow traitors.

The White Scars, the most divided and scattered of the Traitor Legions, still remain a powerful force whose brotherhoods raid far and wide across the galaxy. Though lacking a centralised command and their primarch, many contend for its leadership. Whoever can unite a majority of the V would be the commander of a vast and powerful host that could bring great suffering to the galaxy.

After the Siege of Terra ended in defeat and their homeworld of Fenris destroyed during the Scouring, the Space Wolves withdrew to the Eye of Terror. There on Ymir, a harsh world covered in warp-wrought ice and seas, resides the comatose Leman Russ. The sons of the Sixth Primarch await their father's return, eagerly anticipating his prophesised awakening that would herald the Wolftime and the victory long denied them.

The Imperial Fists' world is of plague and decay. Each Imperial Fist has become a tribute to death, a wandering harbinger of pestilence. This Legion has suffered a schism within its ranks following the First Cadian War, between Dorn and his once favoured son Sigismund, Host of the Destroyer Hive and Herald of Nurgle. Each side seeks to usurp the other in the eyes of the Grandfather and to prove their worth they rot entire worlds for Nurgle's glory.

The Iron Hands have fully given themselves to the Blood God Khorne, living upon a world of blood and metal. Here they improve their bodies with iron in order to find new ways to kill for their lord primarch and god, as well as improve their own savage prowess to further the glory they can bring to the Skull Throne. On their Daemon World of Kronaimok, many Dark Mechanicum hereteks flock to work alongside the Warpsmiths of the Iron Hands, fashioning daemon weapons to sell for slaves and blood. Meanwhile, Ferrus Manus attempts to reforge his metal hands of old, lost to him by his ascension to daemonhood so many millennia ago.

The Ultramarines, unique among the Fallen Nine Legions, have taken refuge not in the Great Eye but rather their once-grand Realm of Ultramar, encased and riddled with the Ruinstorm that Roboute Guilliman created. The Ultramarines, following their father's death on Terra to the blade of Fulgrim, have fractured into a multitude of Chapter-Warbands and rule their own petty fiefdoms within the Five Hundred Worlds. Many worship their father's stasis-preserved corpse on Macragge, seeing their gene-sire as the pinnacle of all they could ever be and as a sacrificial god, but others such as Marius Gage seek to overthrow their long-dead father's influential yoke on the XIII and lead it into a victorious future. From his Fortress World of Armatura, the former First Master begins to deploy weapons, daemon engines, and other fouler creations in his war for supremacy within the Ruinstorm.

The Salamanders seek to free their perpetual daemon father, who became trapped somewhere in the labyrinthine Webway centuries after the Heresy by Magnus the Red. The Eighteenth Primarch calls to his progeny through their blood, causing them to follow his dark urges and commands. The Salamanders murder and burn entire worlds for the glory of Chaos Undivided, all in the search of their gene-sire. It is not uncommon to see some gorge upon the flesh of humans and Space Marines alike, attempting to suppress their father's beckoning. These foul draconic warriors have become cannibals or worse, and there are rumours that the obscene Primarch-Thing of the Black Legion, created by Fabius Bile, longs to claim Vulkan's throne, while others such as Cassian Dracos seek to liberate their brothers from the Drake Lord and forge their own paths, free from failed demigods.

And the Raven Guard reside on their Tzeentch-gifted Daemon World, giving themselves to the Architect of Fate. They experiment on their flesh-change, longing to find some form of perfect stability that constantly eludes them, much to the enjoyment of their dark patron. They raid Space Marine worlds for stocks of gene-seed that they use to experiment upon and unlock the secrets of the Emperor's gene-crafting. To find genetic stability for the XIX has long been the project which has preoccupied the Raven King. If gene-seed stability were to ever be acquired and the Nineteenth Primarch's attention turned elsewhere, then the stars themselves would shake in fear at the horrors that would surely follow.

The Blood Angels, once the vanguard elite of the Great Crusade and then during the Sanguinary Heresy the most favoured Legion of the Ruinous Powers, they are now broken in body, mind, and spirit. For Sanguinius' failure to kill the Emperor and their sudden retreat from the Siege following the Arch-Betrayer's death, the Blood Angels have since been hated by the other Traitor Legions. Such was this fury directed at the Ninth Legion that during the Eye's Legion Wars, the Blood Angels were pushed to the brink of extinction. An extinction staved off only by cunning and fearless warlords and champions bearing Sanguinius' gene-seed, alongside the general lessening of the Slave Wars after centuries of ceaseless battle. Now the Blood Angels are a former shadow of themselves, a hollow remnant of a once mighty Legion, fractured into hundreds of warbands that fight themselves as often as they fight other bloodlines. Greatest of the Blood Angel warlords is Raldoron, former First Captain of the Legion, now Lord Overseer of the Baal Tri-Worlds, every wary of losing his powerbase and begrudging his father's memory, detesting the Angel of Blood for his failures and weakness. But the blood of conquerors and arch-heretics flows through the veins of every Blood Angel and if one worthy enough were able to unite the Legion, then woe betide any who stand against them.

It has been over ten thousand years since the Sanguinary Heresy and the Imperium has endured. Besieged by monsters and xenos, attacked from within by heretics and rebels, assailed by great tragedies such as the War of the Beast and the Reign of Blood that have left scars not yet fully healed. And over the course of those many centuries, the Loyalists Primarchs have either disappeared or died, one by one until finally none of the Emperor's sons now remain.

It is now the late 41st Millennium, the Ork Waaaghs! rampage across the galaxy in numbers not seen since the War of the Beast; the Dark Eldar strike from the shadows, ever eager for slaves and plunder. The deathless Necrons arise to regain their lost throne; while the Tyranids hunger for all life in the stars. And the Tau profess their Greater Good, hoping to bring unity and peace to a galaxy with no desire for it.

The greatest threat to the Imperium however remains the Chaos Legions, who after ten thousand years of disunity and infighting are finally setting aside their differences to take advantage of the Imperium's frailty in the wake of Cicatrix Maledictum's formation that has violently severed the galaxy in two. The Time of Ending approaches, heralding the Last War to come, and the galaxy will burn for it.

A/N: Hey everyone and thanks for reading! This is an alternate Warhammer fanfic inspired by the excellent pieces of work by the likes of Zahariel and Tanner151 (which you should go and read now).

As you can tell this is a what-if the other choice for Warmaster fell to Chaos, and it was the loyalists that were traitors. I intend to the backstory of all the legions in numerical order, but after that who knows. As for why I picked Sanguinius, I thought it'd be interesting to explore how Chaos could have undermined the nature of his mutation. The fear of him not having a place in the Imperium's future and such like.

Anyhow please review as every little helps, and enjoy the rest of your day!

EDIT: Hey everyone, I hope you enjoy the newly-edited chapter. Big shout out to the wonderful Tanner151 who extended out his help in improving the first chapter. Go check out his works, they're awesome!