Pilgrimage of Lorgar

The Pilgrimage of Lorgar was the spiritual quest undertaken by the Primarch Lorgar of the Word Bearers Space Marine Legion during the Great Crusade of the 31st Millennium to discover whether humanity's ancient collective beliefs in supernatural entities were true or whether his father the Emperor of Mankind's athetistic, rationalist Imperial Truth was the correct philosophy to guide Mankind's future. In the course of his Pilgrimage, Lorgar learned that the Emperor had lied and that supernatural entities, the Chaos Gods, did exist. Since they were the only deities seemingly in existence, Lorgar believed that they were worthy of humanity's worship. Lorgar would spend the next 40 years seeking to turn his fellow Primarchs to the service of Chaos and was ultimately responsible for setting in motion the events that brought on the cataclysmic Horus Heresy.

History
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 spiritual entities known as the Chaos Gods.

Prompted by the so-called Pilgrimage of the Primarch Lorgar of the Word Bearers Legion to discover whether or not the Gods once worshipped by adherents of the Old Faith of the Word Bearers' homeworld of Colchis actually existed, Lorgar journeyed with his Word Bearers Legion's Chapter of the Serrated Sun 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 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 rationalist, atheist philosophy of 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, 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 Mankind's natural instinct to seek out the divine as an unworthy superstition and he intended to discover if there were truly deities worthy of humanity'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 Adeptus Custodes who had been set by the Emperor to watch over everything the Word Bearers did to prevent them from falling back into error once more. 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 Expedtionary 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, Adeptus 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 Lorgar Aurelian and welcoming him to Cadia. This woman, the Chaos priestess Ingethel, 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, the Priestess Ingethel of Cadia would initiate a ritual that would see her transformed into the Daemon Prince known as Ingethel the Ascended, and then lead the 1,301st 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 Eldar 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 Eldar 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 29th Millennium to find its worshippers abandoning it out of ignorance and fear, and from the Prince of Pleasure grief was born the endless storm of the Great Eye (the Eye of Terror), an echo of the birth-screams of the Eldar's new and rejected God. The nature of the Primordial Truth was revealed to the Word Bearers in the ashes of the Eldar empire, and Ingethel warned them that in order for humanity as a species to survive they must not commit the same sins the Eldar 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 place where mortals and Gods could meet. Following the visits into the Eye of Terror, Lorgar ordered a cyclonic bombardment of the planet, wiping out the Cadians and leaving 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 dispatched to resettle the world, becoming the ancestors of the present-day 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" 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 Mankind 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 terrible Battle of Istvaan III and the Drop Site Massacre at Istvaan V as well as the larger Horus Heresy itself.