Emperor of Mankind - Horus Heresy: This turn of events did not please all of the Emperor's subjects, several of His primarch gene-sons in particular. In the final stages of the Great Crusade, the Emperor's most trusted son Horus succumbed to the temptations of Chaos. This seduction had been set in place over long solar decades by Primarch Lorgar and his Word Bearers Legion.The idea of "the Pilgrimage," a journey to the legendary place where mortals could directly interact with the gods, was an ancient mythological trope on many Human-settled worlds of the Milky Way Galaxy, including Lorgar and the Word Bearers' homeworld of Colchis. Of course, such a place, the Warp, did exist, and one could discover the Primordial Truth of the universe there, i.e. that the Immaterium was dominated by the powerful psychic entities known as the Chaos Gods.Prompted by the so-called "Pilgrimage of Lorgar" to discover whether or not the gods once worshipped by the adherents of the Old Faith of Colchis actually existed, Lorgar journeyed with the Word Bearers Legion's Serrated Sun Chapter to what was then the fringes of known Imperial space as part of the 1301st Expeditionary Fleet of the Great Crusade.At this time, Lorgar had not yet fallen to the corruption of Chaos, though he had turned against the Emperor of Mankind as a deity no longer worthy of his worship after the Emperor and the Ultramarines had personally humiliated him and the entire Word Bearers Legion on the world of Khur 43 Terran years before the start of the Horus Heresy.The Emperor had come to Khur personally with His Regent, Malcador the Sigillite, after ordering the Ultramarines to destroy the Khurian city of Monarchia where the Emperor was worshipped as a god as a result of the teachings of the Word Bearers. He made his displeasure known to Lorgar about the Word Bearers spreading the religion of Emperor-worship to every world they brought into the Imperium, in direct contravention of the atheist philosophy of the Imperial Truth.The Emperor forced the entire Legion to kneel against their will through the use of His psychic might and then explained that they were the only Astartes Legion to have failed His purpose during the Great Crusade. After this humiliation, Lorgar, on the advice of his First Captain Kor Phaeron and the Word Bearers' First Chaplain Erebus, both already corrupted by Chaos, decided to undertake a pilgrimage to discover if the gods worshipped by the ancient Old Faith of Colchis were real and worthy of the Word Bearers' faith and allegiance.Lorgar believed that the Emperor was wrong to condemn Humanity's natural instinct to seek out the divine as an unworthy superstition and he intended to discover if there were truly deities worthy of Mankind's respect. To this end, though Lorgar no longer had any love or loyalty for the Emperor, he and his XVII Legion rejoined the Great Crusade but did so only for their efforts to serve as a front for their pursuit of the pilgrimage.The Word Bearers were also accompanied on this pilgrimage by 5 members of the Legio Custodes who had been set by the Emperor to watch over everything the Word Bearers did to prevent them from falling back into error. The Word Bearers' pursuit of any scrap of information that could be found on the Primordial Truth or the nature of the place where gods and mortals could mingle ultimately led the 1301st Expeditionary Fleet to the Cadia System near the largest Warp storm in the universe, later known to the Imperium as the Eye of Terror.The expeditionary fleet's master of astropaths advised Lorgar that unusual "voices" in the Warp were heard in the vicinity of the great Warp rift, voices that spoke directly to the primarch as well, which were the voices of the Chaos entities within the Immaterium.It would be in the Cadia System that Lorgar would learn that his suspicions had been correct and that all of the religions across the galaxy that possessed so many similarities to the Colchisian Old Faith were not coincidences, but expressions of worship in the universal truth that was the existence of Chaos.The decision was made to hold orbit over Cadia and for the 1301st Fleet's elements to make planetfall on the unknown world, designated as 1301-12. The landing force was comprised of Imperial Army, Word Bearers, Legio Custodes and Legio Cybernetica elements. The landing party, led by Lorgar, was greeted by a large number of barbaric Human tribes, tribes described as "dressed in rags and wielding spears tipped by flint blades...yet they showed little fear." Most notable were the barbarians' purple eyes, which reflected the colour of the Eye of Terror itself in the spectrum of visible light.Despite the Custodian Vendatha's protests and request to execute the heathens, the Word Bearers approached the natives. A strange woman emerged from the crowd and addressed the primarch directly, calling him by name as Lorgar Aurelian and welcoming him to Cadia.This woman, the Chaos priestess Ingethel of Cadia, would ultimately lead the primarch down a path of spiritual enlightenment that actually marked the beginning of Lorgar's fall to heresy and Chaos. Later, Ingethel would initiate a ritual that would see her transformed into the Daemon Prince known as Ingethel the Ascended, and then lead the 1301st Fleet's scout vessel Orfeo's Lament into the Eye of Terror.Within the Eye of Terror, the Serrated Sun Chapter of the Word Bearers Legion witnessed the failure of the ancient Aeldari Empire first-hand in the form of the Crone Worlds that had been scoured of all life that littered the Eye's region of space. Ingethel, of course, lied to the Word Bearers about how the Chaos God Slaanesh had truly been born and warned that the Aeldari had failed as a species and suffered the Fall because at the moment of their ascension they were unable to accept the Primordial Truth, i.e. worship Chaos.They gave birth to a god of pleasure, yet they had felt no joy at her coming. Their new god, Slaanesh, had awoken to consciousness in the 29st Millennium to find its worshippers abandoning it out of ignorance and fear, and from the Prince of Pleasure's grief was born the endless storm of the Great Eye (the Eye of Terror), an echo of the birth-screams of the Aeldari's new and rejected god.The nature of the Primordial Truth was revealed to the Word Bearers in the ashes of the Aeldari Empire, and Ingethel warned them that in order for Humanity as a species to survive they must not commit the same sins the Aeldari did, and must instead accept the worship of Chaos.The surviving Space Marines of the Word Bearers' Serrated Sun Chapter eventually returned to Cadia and related to Lorgar all that had happened and all that they had learned within the Eye, the true place where mortals and gods could meet. Following his own subsequent visit into the Eye of Terror and his acceptance by the Chaos Gods as their new mortal champion, Lorgar ordered a cyclonic bombardment of the planet. This wiped out the original Cadians and left the planet abandoned so that no others could stumble upon the secret of the Primordial Truth that had been entrusted to him alone by the Chaos Gods.However, the planet's extremely strategic location meant that it would prove useful to the Imperium and in the 32nd Millennium Imperial colonists were despatched to resettle the world, becoming the ancestors of the later population of Cadians. Perhaps as a result of the Eye of Terror's proximity, this later population of Cadians also soon developed the unusual violet-coloured eyes that had marked the first Human inhabitants of the planet.This "truth" of Chaos' existence changed Lorgar and the Word Bearers forever as they were exposed to the Ruinous Powers of Chaos and slowly corrupted, the first of the Legiones Astartes to worship the Chaos Gods and become Traitors to the Emperor in their hearts.Lorgar and the Word Bearers spent the remaining years of the Great Crusade attempting to enlighten Humanity about the true spiritual nature of Creation, ultimately resorting to manipulation and deception to sway nine of the primarchs to the cause of Chaos as their gods demanded, the most notable being the Warmaster Horus. When it became clear that Humanity could not be enlightened by Chaos without first being forcibly weaned at a great price in blood from the Emperor's false Imperial Truth, Lorgar willingly helped orchestrate the events of the Horus Heresy itself.To this end, Lorgar used his Legion's First Chaplain Erebus as his agent. Erebus stole a Chaos-infected blade known as a Kinebrach Anathame from the branch of Humanity called the Interex during the Luna Wolves' brief contact with that technologically-advanced offshoot of Mankind.When Horus and the Luna Wolves personally arrived on the moon of the world of Davin to put down a rebellion against Imperial authority led by the former Planetary Governor Eugen Temba, Erebus made sure that the Anathame ended up in Temba's hands where he could use it to wound Horus. Temba had become a servant of the Plague Lord Nurgle and the moon of Davin was a decaying swamp filled with undead horrors like Plague Zombies created from Temba's Imperial Army garrison who caused Horus and the Luna Wolves no small amount of grief.In a final confrontation on the bridge of his downed Imperial warship, Horus slew the vile Nurglite, but not before the Anathame bit deep into his flesh and delivered a toxin personally created by the Plague Lord, a poison so powerful that not even the primarch's enhanced, superhuman immune system could successfully fight it off. In desperation, the Luna Wolves allowed Erebus to take Horus to the Davinite Lodge Priests of the Temple of the Serpent Lodge, a temple dedicated to Chaos on Davin, who promised that they could heal the Warmaster.During his "healing," the Warmaster's spirit was actually sent into the Immaterium to meet with the Ruinous Powers with Erebus as his guide. Drawing on the primarch's own untapped subconscious wells of ambition and jealousy over his father's seeming abandonment, Horus was shown a vision granted by the Ruinous Powers.This falsely revealed that the reason the Emperor had left the Great Crusade and returned to Terra was so that He could attempt to reach godhood, abandon all His sons and betray the Imperial Truth's promise to enlighten Humanity and free it from the shackles of false gods and organised religion.Believing this vision of the future, which ironically was actually a vision of the Imperium that would only come to pass because of his betrayal of the Emperor, Horus saw it as his duty to save the Imperium of Man from such a fate and turned on his father. He accepted the assistance of the Ruinous Powers in their guise of Chaos Undivided in return for his rebellion against the Emperor.Having corrupted fully half of the Space Marine Legions to the service of Chaos, Horus then led them against the Emperor and plunged the fledgling galactic empire into a colossal civil war that lasted for 7 standard years and began with the terrible betrayals of the Loyalist forces during the Battles of Istvaan III and Istvaan V.This conflict, known to later generations as the Horus Heresy, became the most terrible in Human history, and billions perished as the Traitor Legions tore apart the empire they had helped to forge. The climax of the conflict came during the Siege of Terra, when the Traitor Legions and the other forces of Chaos that they led unsuccessfully assaulted the heart of the Imperial Palace itself.Unable to breach the Inner Palace and the throne room of the Emperor due to the sacrifice of countless Loyalist Astartes and the victory of Primarch Sanguinius over the Bloodthirster Greater Daemon Ka'Bandha, Horus feared that his forces were running out of time as Loyalist reinforcements moved to reach Terra and relieve their compatriots. Hoping to force a final confrontation that would decide the course of the war once and for all, Horus deliberately dropped the Void Shields surrounding his flagship, the Vengeful Spirit, which stood in orbit above the Imperial Throneworld.Throughout all the course of the Horus Heresy, the Emperor had been forced to remain on the mechanism of the Golden Throne. At the start of the Horus Heresy, Primarch Magnus the Red had violated the Edicts of Nikaea to use sorcery to penetrate the psychic wards of the Imperial Palace and bring news of Horus' treachery directly to the Emperor.The Emperor had refused to believe Magnus' warning about His favoured son and instead came to believe that it was Magnus who had been corrupted by Chaos because of his decision to continue to use sorcery in violation of Imperial law.The Emperor had despatched Leman Russ and his Space Wolves Legion to bring Magnus back to Terra to account for his actions, but Horus tampered with the Emperor's orders. Horus' message to the Wolf King so enraged Leman Russ against his sorcerous brother that he ordered the Space Wolves to launch an all-out assault on the Thousand Sons Legion's homeworld of Prospero.This assault, remembered as the Fall of Prospero in 004.M31, ultimately led to the fall of the Thousand Sons and Magnus to the service of the Chaos God Tzeentch in order to save both themselves and all the knowledge they had collected over the centuries.At the same time, Magnus' spell to penetrate the Imperial Palace's psychic wards had also badly damaged the Webway Project, allowing hordes of Daemons to gleefully punch through the Emperor's weakened psychic shield and assault the thousands of Mechanicum workers constructing the Human portions of the Webway.The Legio Custodes and the Sisters of Silence were forced to fight a desperate battle to prevent the Daemons from pouring through the portal generated by the Golden Throne and into the dungeon of the Imperial Palace itself. While the Imperial forces were ultimately successful in fighting back the daemonic assault, only the Emperor was psychically powerful enough to keep the portal closed and the Daemons trapped within the Human-constructed Webway.With His attentions consumed by this crisis, the Emperor left the management of Horus' rebellion to Malcador the Sigillite and Primarch Rogal Dorn of the Imperial Fists Legion. During this time, the Emperor engaged in telepathic communications with the low-ranked Astropath Kai Zulane, who had been granted a precognitive vision of the Horus Heresy's conclusion and the Emperor's terrible fate at the hands of his best-loved son. During their psychic communications, the Emperor revealed He not only had already known what His ultimate fate would be, but had come to accept it as the price of the failure of His ambitions for Humanity.Later Corvus Corax, the primarch of the Raven Guard Legion, deeply distraught over the almost complete annihilation of his Legion during the Drop Site Massacre on Istvaan V, came to the Imperial Palace and demanded an audience with the Emperor. Diverting some of his attention from the strenuous task of maintaining the psychic defences of Terra from the breach in the Webway, the Emperor telepathically imbued the secrets of creating Astartes into his son's mind.Corax then began rebuilding the Raven Guard using these techniques to rapidly accelerate Astartes development, though his efforts were ultimately corrupted by the insidious actions of the Alpha Legion. The Raven Guard would remain one of the so-called Shattered Legions throughout the rest of the Heresy and would play little further part in its outcome.After five standard years of protecting the Human homeworld from the consequences of Magnus' Webway breach while seated on the Golden Throne, the Emperor began to exhibit the first signs of physical fatigue. As the psychic strain worsened, His nose would sometimes bleed, and this image would be projected even in the telepathic visions he sent to his Legio Custodes Custodian Tribune Ra Endymion.After sensing the birth of the powerful daemon Drach'nyen in the Warp, the Emperor knew the War Within the Webway was reaching its climax and the ultimate fate of Humanity would soon be decided. He ordered the Sisters of Silence to gather a thousand psykers across the galaxy and sacrifice them to the Golden Throne.This allowed the device to be powered for a single solar day without the Emperor's presence, and he used that time to plunge into the Webway and rescue the retreating Imperial forces. After sweeping aside the daemonic hordes, He confronted Drach'nyen and sealed it into the body of Ra Endymion, telling his loyal Custodian to run as far as he could into the depths of the Webway in order to keep Humanity safe from the Daemon's influence.Afterwards the Emperor was forced to seal the Webway portal on Terra by again becoming a prisoner to the operation of the Golden Throne. The Emperor lamented to His followers that His great work was ruined and maintained that now that the Webway Project had failed to become a reality, Humanity was doomed to the same fate as the Aeldari, ultimate extinction at the hands of the forces of Chaos.Though the Emperor already knew through his prescient visions that Horus would be defeated at His hands, another Chaos Lord would soon take his place as the Warmaster of Chaos and seek to continue his mission to destroy the Imperium.To the shock of his Custodian Diocletian Coros, the Emperor declared the Imperium of Man to ultimately be doomed, whether it was in a single standard year or ten thousand, and for the first time admitted that even He did not know what to do to save Mankind from extinction.As a result, as the Horus Heresy reached its climax with the Traitors' assault on Terra itself seven standard years after the start of the Warmaster's drive on the Throneworld, the Emperor was forced to remain on the Golden Throne at all times save for the few moments when Malcador the Sigillite, the Regent of Terra and the second strongest Human psyker, could take His place.When the Emperor learned of Horus' action in lowering his flagship the Vengeful Spirit's Void Shields during the final hours of the Siege of Terra, He realised that His treacherous son was actually offering an invitation to battle. The Emperor believed He had to take the war to Horus to put an end to the terrible conflict once and for all.He had Malcador the Sigillite take His place upon the Golden Throne to protect Terra from a daemonic assault through the Imperial Webway portal that lay below the throne and prepared a strike team of Astartes to face the Warmaster on his own ground. The last act of the bloody treachery of the Horus Heresy was played out above Terra, as the Emperor led a desperate assault of Imperial Fists and Blood Angels Space Marines against Horus' Chaos-corrupted flagship, using teleporter technology to make their way aboard.Primarch Sanguinius also accompanied the assault force, but the Warmaster's command over the powers of Chaos caused the attackers to be split up and teleported to random locations throughout the massive warship. Sanguinius reached Horus first and met him in a mighty battle that resulted in his own death at his brother's hands, but not before the angelic primarch managed to create a small gap in the Warmaster's Terminator Armour. The Emperor eventually managed to make His way to the Battle Barge's bridge.Though the Emperor was a being of unfathomable psychic and physical might, Horus had become a being of monstrous strength, bloated with the combined powers of all four Chaos Gods, the true champion of Chaos Undivided, even as the Emperor remained the galaxy's ultimate champion of order.The two champions engaged one another in a tragic battle of father and son, as Horus mortally wounded the Emperor, tearing off one of His arms and shattering His internal organs, largely because the Emperor still loved Horus and could not bring Himself to use the full extent of His psychic abilities to destroy His son.At the critical point in the battle, a lone Legio Custodes warrior who had accompanied the Emperor entered the battleship's bridge, having successfully caught up to his master. Horus flayed him alive with but a look using the potent powers of Chaos sorcery that he now commanded.In that instant of Horus' pure cruelty and casual disregard for Human life, the Emperor finally realised how truly far His favoured son had fallen into the grip of the Ruinous Powers and how Humanity would suffer and ultimately be destroyed under his rule. The sacrifice of the Custodian bought the Emperor the time He needed to deliver a finishing blow to Horus.With iron resolve, He gathered the full strength of His mind at last and delivered a massive psychic attack through the chink in Warmaster's Terminator Armour that killed Horus almost instantly and obliterated his very soul from the Warp so that the Chaos Gods could not resurrect their champion.In his final moments before the Emperor unleashed His final attack to blot Horus' soul from existence, the corrupting powers of Chaos briefly relinquished their hold on the Warmaster's soul and the Emperor sensed the return of His son's sanity in the seconds before his consciousness was utterly obliterated.The Emperor felt only Horus' utter horror at what he had done under the influence of Chaos and gratitude that he had at last been released from its grip before the Warmaster's psyche dissolved into shining motes of psychic energy dispersed amidst the howling voices of the Immaterium.It was in this battered and bleeding state that the Emperor was found by Rogal Dorn, the primarch of the Imperial Fists Legion who had accompanied the assault force onto the Vengeful Spirit. Dorn returned with the Emperor to the Imperial Palace, where Malcador the Sigillite simply crumbled to ash upon relinquishing his place upon the Golden Throne. The Sigillite's body and mind had been burned out by the strain of holding the Golden Throne's portal closed for the time that the Emperor had been aboard the Warmaster's flagship.The dying Emperor quickly dictated plans to Dorn for the modification of the Golden Throne into an arcane life support machine that would sustain His remaining cells in an undying state between life and true death for over ten thousand Terran years, and He was subsequently interred in this altered version of the Golden Throne.The throne's mechanisms would also allow the Emperor to maintain the beacon of the Astronomican and battle the influence of the Chaos Gods in the Warp so long as His mind was empowered and sustained with the psychic energies of 1,000 psykers every day, preventing a daemonic incursion on Terra and helping to sustain Mankind against Chaos' corruptive influence throughout the galaxy.His strength rapidly failing, the Emperor had only enough time to give His final, brief instructions to Rogal Dorn before the Golden Throne's modified mechanisms were activated and He was placed within an unending stasis for more than 10,000 standard years. Only His mind remained active within the Warp as His dying body continued to decay at a glacially slow pace.