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Guilliman Saviour

The resurrected Primarch Roboute Guilliman led the Imperial Crusade known as the Indomitus Crusade that gave the Era Indomitus its name.

The Era Indomitus, also called the Age of the Dark Imperium, is the name given to the present period in the history of the Imperium of Man in the 41st Millennium. It began with the destruction and Fall of Cadia by the forces of Chaos in the 13th Black Crusade and the subsequent formation of the Great Rift across the galaxy.

This period is marked by the physical division of the Imperium into two halves by the Great Rift, the Imperium Nihilus across the northern half of the galaxy where the psychic beacon of the Emperor's Astronomican is no longer visible, and the Imperium Sanctus that included the rest of Imperial space where the Astronomican was still detectable.

This period was defined by the resurrection of Primarch Roboute Guilliman, who took up once more the ruling mantle of the lord commander of the Imperium and Imperial Regent. Guilliman and his ally among the Adeptus Mechanicus Belisarius Cawl initiated the Ultima Founding, which saw the first Primaris Space Marines swell the ranks of the Adeptus Astartes.

With the aid of these new transhuman warriors, Guilliman launched the Indomitus Crusade for which the era is named. An Imperial Crusade on a scale matched only by the original Great Crusade 10,000 years before, the fleets of the Indomitus Crusade spread across the galaxy, defending the Imperium wherever possible from the horde of Chaos and xenos attackers who threatened Humanity with extinction.

Due to temporal instability in realspace created by the birth of the Great Rift and multiple errors in the original Imperial Calendar discovered after Guilliman's resurrection, the Era Indomitus took place at some point between the early 41st and early 42nd Millenniums according to the original chronology set by the Emperor.

Most dates from this era are inconclusive, and are often based on a new localised dating form that used the opening of the Great Rift as the primary marker of the passage of time.

Notable Events

  • Noctis Aeterna - The Noctis Aeterna, also known as "The Blackness" and the "Days of Blinding" in Low Gothic, was a catastrophic event which consumed the Milky Way Galaxy and the Imperium of Man beginning in 999.M41 and lasted at least into the second century of the 42nd Millennium in some regions. The Blackness began following the fall of Cadia at the climax of the 13th Black Crusade and the eruption of the Great Rift that cut the Imperium in half, and was marked by the loss of access to the Astronomican for FTL navigation and a disruption in all astrotelepathic communications. These disruptions endured for variable times across the galaxy, lasting for only thirty-three solar days on Terra itself, but for solar decades or even centuries elsewhere. This period saw more devastating events consume the increasingly isolated worlds of the Human-settled galaxy than at any time since the Age of Strife. Such was the turmoil during the creation of the Great Rift and the period following it that there could be no reliable accounts. As limited communications returned, Historitors and Chronotechs struggled to understand incoming reports. With the influx of Warp energies into such vast regions of realspace, time passed strangely, speeding up in some sectors, slowing in others compared to the sidereal time experienced on Terra, at the heart of the Imperium. These effects on the Warp from the birth of the Great Rift faded with the passage of time, allowing for the reestablishing of interstellar communications with some regions and somewhat more reliable Warp travel. This restoration of stability, combined with the onset of the Imperial counteroffensive known as the Indomitus Crusade, restored the grip of the Emperor over the Imperium Sanctus once more, though the Imperium Nihilus remained largely isolated.
  • Defence of the Cadian Gate - The survivors of the Fall of Cadia reinforce and successfully defend the remaining worlds of the Cadian System and the surrounding star systems of the Cadian Gate from the forces of Abaddon the Despoiler.
  • Chapter Worlds Lost - Contact is lost with slightly less than half of the 1,000 Space Marine Chapters known to be operating across the galaxy at the time the Great Rift was born in ca. 999.M41. Twelve Space Marine Chapter homeworlds are known to be destroyed or overrun during this period, including Pranagar of the Sky Sentinels which was taken by the Daemon Primarch Magnus the Red and his Thousand Sons Traitor Legion, and Sabatine of the White Consuls.
  • Indomitus Crusade - In the wake of the Battle of Lion's Gate, Roboute Guilliman gathers the largest armada seen since the time of the Great Crusade and leads his new Primaris Space Marine Chapters and an alliance of other Imperial forces on a massive counterassault across the galaxy against the forces of Chaos and xenos threats. The Indomitus Crusade's first phase came to an end at the Battle of Raukos twelve standard years after its start. In ca. 012.M42, Lord Commander Guilliman turned his eye to his Realm of Ultramar and its defence from his brother Mortarion and the servants of Nurgle during the Plague Wars.
  • Psychic Awakening - The "Psychic Awakening," also sometimes referred to as the "Age of Witches," is the term given to a phenomenon of the Era Indomitus that dramatically increased the number of new psykers and greatly enhanced existing psychic abilities across the Milky Way Galaxy in the wake of the birth of the Great Rift. While the massive increase in the flow of Warp energy into the local realspace of the galaxy through the Cicatrix Maledictum dramatically enhanced the power and duration of Daemonic incursions, particularly on worlds adjacent to the Great Rift, it also intensified the psychic abilities of the Craftworld Aeldari and the "miraculous" psychic phenomenon that had once rarely accompanied the worship of the Emperor as the god of Humanity. The Psychic Awakening thus proved both a boon and a hindrance to the attempts of the forces of Chaos to overwhelm realspace in the wake of the victory earned in the 13th Black Crusade. For every world that fell to the dominion of the Dark Gods there were also increasing reports of "miracles" in which even individuals who had never manifested the abilities of a psyker were saved by the spontaneous eruption of supernatural abilities. This was particularly true for those servants of the God-Emperor like the Sisters of Battle of the Adepta Sororitas whose unshakable faith in their deity now seemed capable of manifesting into potent mystical protections or miraculous defences against the machinations of Chaos and xenos forces. This phenomenon affected every faction in the galaxy, hindering or advancing the next steps in their various agendas.
  • Hexarchy Rebellion - The "Hexarchy" was a group composed of both current and former High Lords of Terra, many of them removed from office by the Lord Commander of the Imperium Roboute Guilliman after his resurrection, who had refused to accept the reforms the lord commander began to make in the Imperium. The Hexarchy was led by Irthu Haemotalion, a former Master of the Administratum who had been removed by Guilliman and the deposed reactionary Ecclesiarch Baldo Slyst. The group also included the still-seated High Lords Aveliza Drachmar, the Grand Provost Marshal of the Adeptus Arbites, the Lord Commander Militant Mar Av Ashariel, Lord High Admiral Merelda Pereth and the Grand Master of Assassins Fadix. Using the vast resources at their command as the leaders of the Imperium's government, the Hexarchy attempted to forcibly take back control of Terra while Guilliman was away from the Throneworld while commanding the Indomitus Crusade. Once Terra was under their control, the Hexarchy intended to take control of the rest of the Imperium and roll back Guilliman's reforms, ensuring that the unchanging status quo of the so-called "Imperium Eterna" that had reigned before the Era Indomitus began was restored. The Hexarchy ordered the Minotaurs Chapter of Space Marines, known for its unwavering and unreasoning loyalty to the Emperor and the High Lords, to the Throneworld to aid their plot. The Astartes arrived on Terra believing the heart of the Imperium was under siege from enemies within. However, the plotters' attempted coup ended in failure after it was revealed that Fadix's loyalty to the Hexarchy's cause had always been a ruse, arranged from the start by Guilliman to ensure the loyalty of the High Lords he left behind on Terra. Once a signal was given by the grand master of assassins, each of the Hexarchy's members were killed by Fadix's well-placed Imperial Assassins.
  • War Zone Armageddon - As the forces of the Orks and the Imperium were still battling amongst the ruins of the Hive World of Armageddon, the world was overrun by the daemonic legions of Khorne and Tzeentch, which soon began to assault each other as well as anything else in their way. The Greenskins and the Humans were often forced to forge alliances of convenience to defend themselves against their common foe. The arrival of reinforcing Imperial forces, accompanied by elements of nine Space Marine Chapters led by the Salamanders, ultimately succeeded in halting a ritual that would have brought Angron, the Daemon Primarch of the World Eaters, back to the planet that had defied him centuries before during the First War for Armageddon.
  • Fourth Sphere Expansion - The T'au Empire's Fourth Sphere Expansion was aborted by the birth of the Great Rift when its forces were destroyed by the catastrophe sweeping the galaxy. However, once stability had returned to the Immaterium, the T'au would launch their Fifth Sphere Expansion campaign in the early 42nd Millennium.
  • Absorption Wars - It has always been the wish of the Necron Overlord Imotekh to reunite all the Tomb Worlds of the Necron species beneath his rule and nothing could deter his plans, not even rampant Daemonic incursions. As the Great Rift opened, the Stormlord launched his Absorption Wars, a many-pronged campaign to seize dozens of Tomb Worlds awakened by the Warp influx. Imotekh sought to conquer them before they could fully rise from their stasis slumber, ensuring the continued rise of his Sautekh Dynasty.
  • Blood Crusade - The Blood Crusade was a massive offensive unleashed by the forces of Chaos loyal to the Blood God Khorne. His followers -- from daemon legions to brutish beasts to violent-minded hive city Chaos Cultists -- all took up that call to arms. Riding new crests of the Warp Storms known as the "Blood Waves," the daemon legions erupted from the Cicatrix Maledictum, bringing new orgies of slaughter across the galaxy. Thus began the Blood Crusade. The red-raged armies did not seek out destinations. Instead, the gore-slavering fiends merely rode where the storms took them, materialising upon a planet to unleash carnage, and leaving when the tempests moved beyond. Eight distinct spearheads drove out into the galaxy in all directions, and as blood-trails draw in predators, so too did the Blood Crusade.
  • Red Tide - The Red Tide is an enormous Chaos horde that erupted out of the Warp in the wake of the Great Rift's birth. The Red Tide had no plan or agenda beyond destruction, and was simply a carnage-filled crusade of wanton slaughter that carved a bloody path across the galaxy.
  • Invasion of the Stygius Sector - In the wake of the birth of the Great Rift following the 13th Black Crusade of 999.M41, Tzeentch looked upon his brothers. Without plan or agenda, Khorne and Slaanesh were glutting themselves on slaughter and torment, consumed by their rampages, but when Tzeentch saw Nurgle corrupting a whole realm of the galaxy in Ultramar, he grew jealous, seeking as ever to conspire against him, but also wishing to seize star systems for his own. So did the Architect of Fate put a million plans in motion. The Crystal Stars intrigued Tzeentch, as did the Shrouded Zone. It was the Stygius Sector, however, that he would attempt to claim first. It was in the Segmentum Obscurus, near the Eye of Terror and cut off from the Light of the Emperor's Astronomican during the Noctis Aeterna. There, entropy raged the fiercest, and amidst the maelstrom of unnatural energies the tightly packed pattern of nine-times-nine star systems called out irresistibly to Tzeentch. Though the assault was contested by a powerful Imperial force and even aid from the Aeldari of Craftworld Ulthwe, the sector was ultimately surrendered to Tzeentch, who saw it as only the first of the regions of realspace he intended to claim for his own.
  • Final Dawn of Rykad - Not long after the birth of the Great Rift in the Era Indomitus isolated the Koronus Expanse in the Imperium Nihilus, a heretical Chaos Cult emerged in the Rykad System, part of the sphere of influence of the Rogue Trader House vWinterscale, led by a "prophet" named Aurora who foretold of an event called the "Final Dawn." Amidst a planet-wide uprising unleashed by the cult on the system's capital world of Rykad Minoris, Aurora led an attack on the Electrodynamic Cenobium, a temple of the Adeptus Mechanicus housing an archeotech plasma reactor, which she attempted to overload. Aurora was seemingly killed by a strike team led by the Rogue Trader von Valancius dynasty's recently installed Lord Captain who had come to the world seeking aid after the loss of their flagship's Navigator to a Warp incursion. The Rogue Trader and their retinue aided the world's Winterscale defenders in crushing the rebellion; however, during a triumph thrown in the new Rogue Trader's honour, the planet's sun suddenly went dark, stolen by Drukhari warships for use in Commorragh. Seeing this as a signal, the Final Dawn cult mounted a final assault on the capital city of Rykad Minoris as the veil between realspace and the Immaterium thinned. The von Valancius Rogue Trader and their retinue fought their way to Rykad Minoris' starport, to be confronted on the landing pad by a Word Bearer Chaos Champion, who stated that it was he who had really been "Aurora" all along. After a pitched battle, the Rogue Trader slew the real "Aurora", but was forced to flee the dying star system in their flagship. The Word Bearers had succeeded in weakening Imperial influence in the region.
  • Talledus War - The Talledus War was a War of Faith fought in the Era Indomitus between the forces of Chaos and the Imperium of Man to defend the Shrine World of Benediction in the Talledus System of the Veritus Sub-sector. Though Benediction was the Chaos forces' primary target, all the inhabited worlds of the system faced a large-scale assault led by the Dark Apostle Kor Phaeron of the Word Bearers Traitor Legion. The Word Bearers, as always, sought to convert the bulk of Humanity to the service and worship of the Chaos Gods. They took great pleasure in furthering this agenda by attacking a world and system that was of such importance to the Imperial state religion that they deemed a fraud. The fall of Talledus and Benediction to Chaos, and the conversion of its people to the true faith of Chaos, were deemed a potentially major milestone in the Word Bearers' plan to throw down the Corpse God of the Imperium and claim Mankind for the Dark Gods. The war proceeded on three fronts, on Benediction, on the Astra Militarum Fortress World of Ghreddask and in the void surrounding the asteroid belt called the Tears of the Emperor at the very edge of the system. On Benediction, the Word Bearers forces commanded by Kor Phaeron nearly seized control of the Grand Honorificum cathedral-city complex. The Loyalists were saved by an unusual phenomenon that was part of the Psychic Awakening when the faith of those gathered in the cathedral summoned forth from the Warp the protective spirits of the sacred Imperial dead. This supernatural force, later remembered as the "Saints' Wall," surrounded the Grand Honorificum in a protective psychic shield and extinguished the grip on reality held by many of the daemons making up Kor Phaeron's attacking army. This miracle allowed a demi-company of Salamanders Astartes to cut the remaining force of Chaos troops in two and establish a new defensive perimeter for the cathedral complex. On Ghreddask, the intervention of a Black Templars strike force destroyed the Soul Harvester mobile fortress-factory that had left the Imperial defenders at a loss, though the suicidal counterassault cost the life of the Astartes commander, Castellan Dramos. In the void, within the Tears of the Emperor, a piratical Night Lords fleet commanded by the battleship Nightmare of Celyx sought to draw in Imperial military and commercial shipping translating into the system from the Warp by using captured Imperial astropaths to throw off their Navigators' abilities. The Night Lords then took the spoils and reaped with great pleasure the terror of their victims. The arrival of Vanguard Marines from the White Scars' 10th Brotherhood turned the tables on the Heretic Astartes pirates. Their hit-and-run strikes soon transformed into a vicious, void-based guerilla war as each side tried to lure the other into ambushes. The White Scars succeeded in blunting the Night Lords' attacks on incoming Imperial shipping, but were unable to annihilate the Chaos raiding force entirely. Though the Imperium has so far managed to blunt the Chaos assault on the Talledus System on every front, the conflict is far from over.
  • Third War for Damnos - The Third War for Damnos began when an invasion force of the Necron Szarekhan Dynasty descended upon the Mining World of Damnos during the Era Indomitus. The Human settlers of that world sent out a plea for aid once more to the Ultramarines, who at that time were engaged in a number of major conflicts of the era, including the Indomitus Crusade, the Plague Wars and the War of Beasts. With most of their strength utilised elsewhere, the Chapter had few Astartes to spare to help the besieged planet. Nonetheless, the Chapter had given too much previously in Damnos' defence to abandon it and a small strike force of Ultramarines and several regiments of the Ultramar Auxilia were sent to aid it. The Chapter knew that the forces that had been deployed to Damnos would be insufficient to defeat the Necrons and so requested aid from their allies in different Chapters. Their requests were answered and when the Ultramarines arrived at Damnos they were joined by contingents from several Successor Chapters, including the Iron Hounds, Brazen Consuls and Libators. Their combined might of these Adeptus Astartes, however, was not enough to defeat the invading Szarekhan Dynasty, whose forces were numberless. This was due to the undying xenos arriving in their thousands by Tomb Ships and through a Dolmen Gate to ensure they reconquered Damnos. When the Mandeville Point for the Damnos System once again flared as it opened to the Warp, the Ultramarines feared that another foe was about to join conflict, but instead it marked the arrival of reinforcements sent by the Salamanders and White Scars Chapters. They had received the Ultramarines' request for aid and proceeded to join the battle to retake Damnos once more for the Emperor from the Szarekhan Dynasty.
  • Plague Wars - The Plague Wars were the result of Nurgle's desire to claim the Realm of Ultramar for his own. After the creation of the Great Rift, the forces of the Plague God, led by his foremost champion, the Daemon Primarch Mortarion of the Death Guard Traitor Legion, claimed the Scourge Stars, a trio of star systems from which Mortarion led his invasion of Ultramar. The wars raged for several standard years across Ultramar as the Imperial defenders slowly lost ground. The Chaos offensive was finally brought to a halt by the return of Roboute Guilliman and his forces in ca. 012.M42. The battle between the former brothers ultimately resulted in a draw on Iax, though the conflict remains ongoing.
  • Fourth Tyrannic War - The Fourth Tyrannic War began when the largest mass of Hive Fleet Leviathan yet encountered attacked the Western Reaches of the Segmentum Pacificus, seeking to strike at a relatively undefended region of the galaxy while the defenders of the Imperium were otherwise engaged with the forces of Chaos emanating out of the Great Rift. The great Tyranid assault began with the coordinated attack from above and below the galactic plane by three new tendrils of the Leviathan dubbed Hive Fleet Nautilon, Hive Fleet Promethor, and Hive Fleet Grendyllus, respectively, by the Imperium. The two tendrils were moving in parallel towards their ultimate goal of Terra in the Segmentum Solar, and with the Imperium distracted by the demands of the Indomitus Crusade few Human forces initially were available to stand against it.

Canon Conflict

As originally chronicled in the Dark Imperium novel series by Guy Haley published in 2017-2018 early in the 8th Edition of Warhammer 40,000, the Indomitus Crusade lasted for roughly 100 standard years and ended with the Plague Wars.

However in 2021 Black Library retconned the events of the novels to take place only 12 standard years after the crusade had begun, now with no end date for the conflict.

This change now places the events of the Plague Wars in circa 012.M42 early in the Indomitus Crusade by the chronology of the original Imperial Calendar.



  • Codex Adeptus Astartes - Space Marines (8th Edition), pg. 19
  • Codex: Astra Militarum (9th Edition), pg. 11
  • Dark Imperium (Novel) by Guy Haley
  • Warhammer 40,000: Rulebook (8th Edition), pp. 50-53, 123, 134, 152, 164-166
  • Watchers of the Throne: The Emperor's Legion (Novel) by Chris Wraight, Ch. 5
  • Imperium Nihilus - Vigilus Defiant (8th Edition), pp. 5-20
  • Psychic Awakening: Faith & Fury (8th Edition), pp. 8-19
  • Codex: Space Marines (9th Edition), pg. 58
  • Watchers of the Throne: The Regent's Shadow (Novel) by Chris Wraight, Chs. 14, 16-17, 20-22, 28
  • Warhammer 40,000: Rogue Trader (PC Game)
  • Warhammer 40,000: Leviathan - Rulebook (10th Edition), pp. 222-255
  • The Warhammer Preview Online: Black Library, Interview with Guy Haley December 5, 2020
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