- "Butcher your enemy's warriors without mercy. Crush his armies and leave none alive. But do not stop there. Burn his cities. Bomb his worlds from orbit. Slaughter everything and everyone until he kneels in the ashes of those he sought to protect. Only then will he understand the true fury of the Dark Gods."
- —Haakor of the Black Legion
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.
However, the price paid proved steep. Slightly less than half of the one thousand Space Marine Chapters known to operate across the galaxy remained unaccounted for, and no less than twelve Space Marine Chapter homeworlds were reported as destroyed during the Noctis Aeterna and the equally bitter campaigns that followed.
As the chain reaction of the Great Rift cracked open the galaxy, tidal waves of unnatural energies spilled outwards in sporadic fashion. Warp Storms swept across everything -- not even the furthest reaches of the galaxy were spared their corrupting touch. With a great surge, over a million planets of the Imperium were cut off from the Light of the Emperor as the Astronomican went out.
During that time, the Imperium of Mankind ceased to be -- each planet was isolated, a speck of sanity buffeted by a raging tempest. It was a Warp Storm beyond the ability of any technology in the Imperium to record -- indeed, it was greater in size and power than anything that had ever been recorded, the most powerful of its kind since perhaps the lost era of the Age of Strife.
During the Blackness, as many came to know it, all long-ranged astrocommunications proved impossible. The Warp was in far too much upheaval to permit travel, and those starships in transit at the time were destroyed in horrific fashion or subjected to the worst battering their crews had ever experienced. It is impossible to count all those who lost their lives in the turmoil. Those who survived found themselves carried far off-course by the insane tides of unnatural energies.
Riding the crest of the Warp Storms' shock waves, or following swiftly in their wake, came the Forces of Chaos. The daemon legions were the vanguard, followed hard by the fleets of the Traitor Legions and the ragged masses of the Renegades and their associated Chaos Cults.
The Defence of Terra
As the first Warp Storms broke over Holy Terra, its pollution-filled skies turned a roiling crimson. Khorne, heedless of the plans of his brother gods and hungry to prove his superiority in the Great Game, sent forth eighty-eight cohorts of his daemon legions to assault the Imperial Palace. The Blood God wanted the glory of tearing down the Golden Throne for himself, and so the skies of Terra congealed into bloodclouds that deployed the Red Host directly before the Lion's Gate.
The gun batteries of the Imperial Palace are second to none, yet they alone could not halt this red tide. Led by Roboute Guilliman, the newly reappointed Lord Commander of the Imperium, the Primaris Space Marines, Adeptus Custodes and Sisters of Silence fought side by side. Although the rash Chaos assault was turned back and broken long before it could reach the Eternity Gate to the Inner Palace, the High Lords of Terra were shaken at the boldness of the foe.
Without the beam of the Astronomican, their arcane machinery and protective devices were not enough to halt the fell powers from materialising even on Holy Terra. Khorne, upon receiving the returning forms of his slain, grew so apoplectic in his rage that his fortress in the Realm of Chaos trembled. So great was the heat from his outburst that the essences of the eight Bloodthirsters that led the failed attack were wholly obliterated.
The Cadian Gate is Broken
Cadia had stood so long, and so proudly. The gate through which the enemy could not pass. For the whole Age of the Imperium, that bastion planet bore the brunt of countless Chaos assaults as the daemonic forces attempted to reach Terra. Cadia, and the fortified worlds of its system, were for long centuries a redoubt that withstood every horror that issued from the Eye of Terror. In the Dark Imperium there was no assurance, however, from which direction the Chaos forces would attack; the only assurance was that they would.
Although Cadia was ultimately reduced to a burning wasteland by Abaddon the Despoiler's endless assaults during the 13th Black Crusade in 999.M41, the worlds in the wider Cadian System fought hard to destroy the spearhead the Despoiler had plunged into their midst. The Great Exodus of Cadia had seen swathes of the Imperial defence redeployed to the sister planets of the lost Fortress World, and not before time.
Every realm touched by the Cicatrix Maledictum was blighted by intense Daemon Storms, howling tempests that carried a thousand types of death upon their fell winds. Where those baleful hurricanes blew strongest, the scions of the Dark Gods would stride from the aether and bring battle anew to the defenders of Mankind's realm. Hundreds of battles. Uncounted billions of casualties.
The skies of Belis Corona were lit with fire as the conquering fleets of Abaddon's endless armadas clashed with the Imperial Navy battlefleets of the Segmentum Obscurus. The Forge World of Agripinaa, its legions bold enough to have raided the Eye of Terror in the past, was assailed by covetous Warpsmiths and the menageries of Daemon Engines that stormed forth at their behest. Again and again the stakes were raised as the forces of Chaos rode upon the winds of the Great Rift.
The Hour of the Legion of the Damned
Although all communications were cut, they received the distress calls. When travel was impossible, they arrived unlooked for. When all hope was lost, they strode forth out of the Blackness, a legion of vengeance, a brotherhood of flame.
The spectral Legion of the Damned appeared on Baal, Armageddon, Antagonis and hundreds more planets besides. They spoke only with Bolter and Chainsword, meting out terrible punishments upon the enemies of the Imperium before themselves vanishing without a trace. Truly the hour of the damned had come at last...
A Light in the Darkness
From blackness there came a light. A brief flash, then distant blinks. Intermittently, the rays of the Astronomican lanced outwards from Holy Terra. Deeply the psychic beam pierced the maelstrom that smothered the galaxy, but it could not pierce the Great Rift.
In the northeastern half of the galaxy, they could see little or none of the Emperor's guiding light -- the Cicatrix Maledictum simply swallowed its illumination. Now that messages could once again be sent through the Warp, Terra received such a backlog of terror-filled psychic shrieks that half of the already-depleted Astropath core were instantly driven insane. The survivors were appalled to discover how many planets, even on the accessible Terran side of the Great Rift -- the Imperium Sanctus -- did not respond.
Slightly less than half of the one thousand Space Marine Chapters remained unaccounted for, and no less than twelve Chapter Planets were reported as destroyed during the Noctis Aeterna and the bitter campaigns that followed. Some Space Marines, like the White Consuls, escaped the destructions of their fortress worlds. Others died to a man, as did the Sky Sentinels, when their homeworld of Pranagar was overrun by none other than Magnus the Red, Daemon Primarch of the Thousand Sons.
Should the isolated Imperium Nihilus regain contact with Terra, the number of known losses will only grow, as the High Lords of Terra learn the grim truth.
The Indomitus Crusade
After his defence of Holy Terra, Roboute Guilliman gathered a new armada that he named the Indomitus Crusade, the largest concentration of Imperial military forces seen since the original Great Crusade over ten thousand standard years before. Along with elements of the Adeptus Custodes, a small contingent of the Silent Sisterhood, and a vast war host of Primaris Space Marines from many newly founded Chapters and the Legions of the Unnumbered Sons, the Primarch set a winding course.
Strike forces from over a dozen pre-existing Chapters of Space Marines, led by the Imperial Fists, joined the fleet. Thus began many new legends as Guilliman travelled to aid beleaguered planets, breaking sieges and sweeping away Chaos and xenos invaders alike to bring hope back to the desperate defenders. It was not long before word began to spread, as all those planets that could still receive astropathic messages hailed the return of a hero out of myth.
Once more, one of the demigods of the past fought for the Imperium of Mankind. The Indomitus Crusade would reach its end over a century into the 42nd Millennium at the Battle of Raukos. Afterwards, Guilliman would turn his attention to helping his Realm of Ultramar defeat the forces of the Death Guard Traitor Legion and the servants of Nurgle in the Plague Wars.
A New Breed
In a hundred war zones, untested strike forces of Primaris Astartes are unleashed into battle against the forces of the Ruinous Powers. They acquit themselves well, and by the artifice of Archmagos Dominus Belisarius Cawl and the strategic genius of Guilliman they prove themselves worthy inheritors of the title Adeptus Astartes.
The Stand at Armageddon
For much of the 41st Millennium the planet of Armageddon had been a battleground. First invaded by Chaos, it was later the site for a massive war between the Ork hordes of Ghazghkull Thraka and the forces of the Imperium. Although the infamous Greenskin leader left to establish new stomping grounds in the wake of the Third War for Armageddon, the onslaught continued. Not even the hellstorms unleashed by the Great Rift could halt the fighting, but they did change its nature.
During the Noctis Aeterna, reinforcements were cut off for both sides, and those en route to the system were swept into oblivion. Those that remained on Armageddon were forced to fight off not just each other, but the oncoming waves of daemons. At times, so desperate were the defenders that Ork and humans fought alongside each other against the greater threat. Such temporary ceasefires never lasted long.
By the time the Astronomican returned and travel through the storm-ridden Immaterium was once again possible, the Imperial relief force arrived to find the landscape greatly changed. At the height of the Warp Storms, the forces of Tzeentch and Khorne had battled each other on Armageddon's blasted surface. The Orks and Imperial forces sought cover as titanic Greater Daemons duelled for supremacy.
The Imperial forces, with elements of nine Space Marine Chapters led by the Salamanders, succeeded in halting the 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.
The Devastation of Baal
After sacrificing the Shieldworlds of the Cryptus System to fend off the xenos' earliest advance on the Baal System, the planet of Baal itself came under intense attack by Hive Fleet Leviathan. The Tyranid Hive Fleet was of such mass, even after its considerable losses, that it blotted the stars from the skies.
Lord Commander Dante bolstered the formidable defences of the Blood Angels' homeworld and its moons like never before. Not one to await attack, he also sent forth scores of preemptive strike forces to delay, mislead, and whittle down the living armada. Hundreds of splinter fleets were thus defeated.
Dante's call, beseeching the Blood Angels' Successors to send immediate aid to their parent Chapter, did not go unheeded. The Flesh Tearers were the first to arrive, and ultimately all the Successor Chapters save the Lamenters answered the call. Even the Knights of Blood, who had been declared Excommunicate Traitoris by the High Lords of Terra, arrived to bolster the defences. It was still not enough.
Learning at an exponential rate, Hive Fleet Leviathan could not be thwarted by the same strategy twice. Advancing steadily, their superior numbers cleared the entire surrounding sector of life before the xenos made planetfall upon Baal and her twin moons. The first nineteen waves, each larger than the last, were driven off at great loss to the Blood Angels and their Successor allies.
Five Chapter Masters fell in that bitter fighting, three in the Battle at the Dome of Angels alone. The Tyranids began the process of absorbing all biomass from Baal and its moons, absorbing even the radiation-poisoned deserts of Baal Secundus. With their defences in ruin and Baal's moons stripped and broken, the remaining Space Marines retreated back to the rubble of the Blood Angels' sprawling fortress-monastery. There, they prepared for a last stand as the next wave swept downwards. Doom, it seemed, had at last come to the Sons of Sanguinius.
It was then that the Great Rift cracked open the galaxy in the wake of the fall of Cadia to the 13th Black Crusade, and the withered Baal System was blasted by the aetheric storms. Although no further attack waves came from the Leviathan Hive Fleet, not a single Imperial defender remained alive upon the last moon, Baal Prime.
On Baal itself there were already enough Tyranids there to destroy the Imperial troops many times over. Even with no chance of victory, Commander Dante led his troops, each fighting retreat seemingly more hopeless than the last. As the final perimeter was broken, the stars reappeared.
Looking skywards, the Tyranids on the surface of Baal sought contact with their Hive Fleet, but it was gone, replaced by a newly arrived Imperial fleet. Like an angel of vengeance came Roboute Guilliman and his Indomitus Crusade. After many more battles, Baal was finally cleared of the xenos threat. A great rebuilding of both world and Chapter was undertaken, for the Blood Angels and their Successors were sorely needed elsewhere in the beleaguered Imperium.
What became of the Leviathan is a mystery, although a clue was found upon the now-barren moon of Baal Prime. Xenos skulls were piled impossibly high in the much-reviled, eight-pillared symbol of one of the Blood Angels' most terrible and ancient nemeses: the Bloodthirster Ka'Bandha and his army of Khornate daemons.
In an effort to seize the initiative, a strike force was mustered on Terra, supported by an entire army of Adeptus Custodes. The Custodes, for long millennia the bodyguard of the Emperor who had refused to leave His side or the Imperial Palace no matter the danger to His Imperium, were now charged with the once-unthinkable -- to leave his side and strike against those who would see the Master of Mankind dead.
The Plague Wars
Something terrible came out of the Warp Storms as they roiled through the southern reaches of the Ultima Segmentum. Where the seeds of corruption had been planted by Nurgle, a new and terrible contamination spread. The diseased dead rose to claim the living.
Previously, the walking corpses could be destroyed, but now doing so only released hordes of Nurglings that writhed impossibly out of the withered flesh of the fallen. Hive Worlds were toppled, and as the Blackness descended, there was no escape. In the horrific ruins, Cults of Corruption slithered out of hiding, summoning forth further aid from the Realm of Chaos itself.
So did star systems fall, creating the Scourge Stars -- a trio of sickly systems that had fallen to the Plague Lord. From that power base, the Death Guard and legions of plague daemons issued, systematically reaping planet after planet. On they spread.
It was none other than the Daemon Primarch Mortarion that brought the fabled Realm of Ultramar, gem of the whole segmentum, under siege. Plague bombardments rained down, so severe that once gloried hive cities became pits and Agri-worlds became slime-ridden ruins. Chaos was encroaching on many fronts when Roboute Guilliman returned from Terra after the end of his Indomitus Crusade at the Battle of Raukos over a century into the 42nd Millennium.
It was his tactical acumen that first stabilised the many war fronts, and his Spear of Espandor counterattack successfully bought the forces of the Imperium still more time. At the Gates of Parmenio, Roboute Guilliman defeated the Greater Daemon Septicus and his Plague Guard. At Iax, once a glorious Garden World, Primarch met Primarch as Guilliman confronted Mortarion, the two brothers fighting to a deadlock before the Chaos forces mysteriously withdrew under cover of a virus bomb.
To Shield the Shrine Worlds
In an attempt to break the sieges that hold dozens of Shrine Worlds hostage across Segmentums Solar and Pacificus, the Black Templars launch Crusade after Crusade. In their bloody endeavours they are assisted by the Iron Hands and a score of other Space Marine Chapters, along with all the forces the Adeptus Ministorum can muster.
The Nachmund Gauntlet
An intermittent passage through the Great Rift was discovered, yet it brought little hope to the Imperium. The Cicatrix Maledictum had at least one gap, although others were reported but not confirmed. The passage was near the Eye of Terror, which had been avoided by Navigators since the Great Crusade, for Warp Storms and strange anomalies had always made the region too dangerous to travel. There, when the swirling nebula lulled, was revealed the Nachmund System, near to Agripinaa on the near side of the rift.
Its Tyrant King, Kaligius, ruled over a house of Chaos Knights that had not been seen since the Horus Heresy. Claiming Old Night had returned to plague the galaxy once more, Kaligius rejected communications from the Imperium, instead making pacts with Renegades and pirate fleets.
Some starships have run the Nachmund Gauntlet successfully, but many more have been destroyed attempting the journey -- the ruined hulks of innumerable craft hang suspended in space as a voidship graveyard.
As the Imperium gradually realised the extent of the nightmare conditions created by the Great Rift, its people tried to adapt to the horrifying new dynamic. There were no more shield worlds, no more bastion systems.
Every planet of the Emperor's realm -- even Holy Terra itself -- was now on the front line of the war for Humanity's survival in the face of predatory daemons and aliens.
Thus did a dark age grow ever more bleak -- and the fight had only begun.
Notable Events of the Noctis Aeterna
- Battle of Lion's Gate - Roboute Guilliman defeats a massive daemonic assault by the forces of Khorne upon the Imperial Palace. After the Battle of Lion's Gate, informally known as the Second Battle of Terra, the High Lords of Terra realised that no place in the Imperium was now safe from an assault by the Archenemy.
- 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.
- Defence of the Damned - The Legion of the Damned appears to aid desperate Imperial defenders on more than a hundred worlds, including Baal and Armageddon.
- 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 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 the Thousand Sons Traitor Legion, and Sabatine of the White Consuls.
- To Shield the Shrine Worlds - Shrine Worlds of the Imperial Cult come under assault by Heretic Astartes and daemons across the Segmentum Solar and Segmentum Pacificus. The Word Bearers Traitor Legion is especially active in this endeavour. To combat the servants of the Ruinous Powers and end this blasphemy, the Black Templars Chapter takes it upon itself to launch Imperial Crusade after Crusade to retake each world. They are often joined by the Iron Hands, a score of other Adeptus Astartes Chapters, and whatever forces the Ecclesiarchy can muster.
- 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 lasted for over a standard century and came to an end at the Battle of Raukos. After its end, 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.
- War of Beasts - The strategically located Hive World of Vigilus linked the Imperium Nihilus with the Imperium Sanctus through the Nachmund Gauntlet, one of the only known stable passes through the Great Rift. Realising the importance of this planet to the survival of the Imperium, it was assaulted by multiple xenos and Chaos forces, including the Black Legion under the command of Abaddon the Despoiler. Though the Despoiler's invasion was ultimately defeated by warriors drawn from multiple Space Marine Chapters under the command of the Ultramarines Chapter Master Marneus Calgar, Vigilus remained a world largely under siege from Ork, Drukhari and Genestealer Cult factions.
- 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.
- Devastation of Baal - With the arrival of Roboute Guilliman's Indomitus Crusade, the Blood Angels and their Successor Chapters are successful in fending off the great assault of Hive Fleet Leviathan upon their homeworld of Baal. The remainder of the Leviathan is largely consumed by a Warp Storm and a great assault of Khorne daemons led by the Blood Angels' ancient foe, the Bloodthirster Ka'bandha.
- 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 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.
- 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 solar decades across Ultramar as the Imperial defenders slowly lost ground. The Chaos offensive was finally brought to a halt by the return of Roboute Guilliman following the end of his Indomitus Crusade in the early second century of the 42nd Millennium. The battle between the former brothers ultimately resulted in a draw on Iax, though the conflict remains ongoing.
- Age of Strife
- Great Rift
- Imperium Nihilus
- Indomitus Crusade
- War of Beasts
- Plague Wars
- Codex Adeptus Astartes - Space Marines (8th Edition), pg. 19
- 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