In 003M42, there was still hope. Of course, those who knew relatively well the machinations of the Warp killed it from their hearts, replacing it with the grimness of survival for the Imperium and the Emperor. Those fell first.
As the new God was born, Cadia fell first, and with it, all of the Cadians. The once battered world was now bathed in shadow and darkness, its steadfast inhabitants remaining resolute in front of the coming apocalypse. But no longer for the Emperor. Now they had someone, something, that could understand them better than the Emperor. The Emperor and His lackeys had given them this drive to fight until now, but now, something greater emerged and none dared or wanted to fight it even if they could.
Cadia became the first Daemon World of the God of Grimdarkness and the "meeting" center of a new Eye of Terror. But strangely enough to the observers after, it did not expand into Imperial territory further than the old one. Instead, it cannibalized Slaneesh's realm. The youngest of the Greater God screamed in anguish and impotent rage as its beautiful creation, its gift to Fulgrim's peacocks, was marred by all-consuming darkness, ever expanding on his former beautiful red-purple orb that had shined over, terrorized and mesmerized at the same time an entire Galaxy and that had been visible until so long from other galaxies, even distant ones, defying gravity, light dispersal theory and other physical laws to anyone who'd see it even across the Universe. This new Eye looked more like an all-compassing black hole, though it only ate light and not the creatures and ships in it, and its inhabitants watched the change mostly uncaring - they had seen worse and the ways of the Warp were always fickle and changing, as well as aliagences.
But the worst hit was indeed the Imperium. Around half of its already depleted forces had turned in the span of a Terran second. From the Guard to the Navy to the Space Marines, Inquisition and Ecclesiarchy, none were safe anymore. When analyzed later, it would be postulated that the reason those thought beyond reproach had turned and defected was not because their loyalty in the Emperor had been destroyed by the foul blackness from the Warp, but because they had not really believed in the Emperor as a man, a god or a savior, but in the idea of merely holding the line and fighting against all odds for their survival and that of their families. It has been further speculated that even the belief in Humanity as a whole would have saved them from corruption. But alas, they were discovered way too late to not believe in any of that, but in an idea and ideal. And oh were those so easily corruptible and mendable by Chaos.
The result of the second "exodus" were dire indeed. The first to fall, almost on the second of the birth of the entity (presumable either at the same time or milliseconds after the Cadians), were all the gene-sons of Dorn. There was not one exception from the dour Astartes as, from Chapter Master to lowly scout and even chapter serf decided on a direct way to the new Daemon World from whatever assignment they were sent to or any engagement they were into. It is said that the Black Templars were the most ardent of these new recruits from the Emperor's light and into the Warp's darkness.
The Dark Angels followed suit, minutes after the psychic scream of the thing. Though apparently undecided for those minutes, they took the path to the Eye, taking the remains of their ancient world with them.
Most other Chapters had internal conflicts, but some were, luckily or unluckily, in scattered Companies when the event happened and some Companies decided in mass to defect, while others to stay true to the Emperor's light. There had been noted incidents with alarming regularity of entire Chapters to simply up and leave, or even individual Marines or groups of serfs, not deeming to answer to their brothers. To the later dismay of Imperial authorities, some were simply let go, their loyalist brothers either not seeing the threat for what it was or seeing it and deciding not to do anything more than hold the line themselves to the light of the Emperor and let the fallen leave quietly for their chosen darkness. It is said the Blood Ravens and Silver Skulls let or avoided entire companies from other Chapter to leave to the Eye when they had the opportunity to stop them, at the behest of their Librarians. No sanction had been made against any of these acts, for both fear of yet another rebellion, the need of warm bodies between the Imperium and the new/old Eye, as well as all the other enemies of man. There were also voices that considered this resonation through much of the Imperial forces to not do anything against their fallen brothers a direct message from the Emperor that may have saved countless Imperial lives. In normal times, these would be yelled at as heretical, but in this time of uncertainty, when one more weapon was stolen from Humanity and its Emperor, few things could still be denied.
Of course, many stayed true en mass as well. The Space Wolves, though dour and aggressive in battle, and didn't see the Emperor as a God, were also jovial and joyful in celebration, and it is assumed this saved them from the path of darkness. It is to be noted that although all of Dorn's legacy had fallen, all of Russ', with no exception, stayed loyal to the Emperor and the Imperium. Some of their serfs succumbed however and they were quickly taken care of by the joined forces of the mortals and Astartes alike. Most of the Blood Angels' legacy did the same, though there had been reports of at least a few Blood Angels up and leaving battlefields without warning, reason or indeed retaliation against their former brothers and heading to the newest Daemon World to join their new master. Serfs were put down, but worse, a full scale revolt erupted on Baal, and the Blood Angels were forced to require a third time help to their sister/child Chapters, which sparked even more tensions between them and brought harsh words from the mouth of the Flesh Tearer's Chapter Master. But in the end, they all recognized that Sanguinius' blood stayed true in the First Founding Chapter as there was as little defection from them as there was from the rest of the sister Chapters. It has been speculated that what almost condemned them to Khorne during the Horus Heresy actually saved them in this occasion: their mentality was incompatible with Grimdark and a lot more with Khorne, as demonstrated and taken to its extreme by the Flesh Tearers. Either Grimdark didn't want them, or they didn't want that Darkness to fill them, for their thirst was for blood, and apparently, Grimdark would have none of this.
A major blow however came from and to the Ultramarines, as it had half its strength, as well as half of each of its successor chapters, literally walk away to form a new host. They now call themselves the Strongmarines and left to find, populate and create a new Imperium in a world they decided even as they left to name Strongmar. Probably the worst was though, that Calgar led these "awakened" as it was recently termed into the Eye, though not before having words with Tigurius. Whatever had been said is a closely guarded secret of the Ultramarines, though it is suspected some daemons and possible all the new defecting Marines know too well, but whatever it was, it didn't lead them to blows and Tigurius let him go. At least Calgar agreed to leave Guilliman's body on Ultramar and has been loosly quoted as not having any interest in ever wanting to take it for himself or as a symbol of his new Legion. The Strongmarines are now feared to be on par with the strongest known Legion in the Eye, the Word Bearers, possibly numbering more than the former's assumed 60.000 strong.
Another notable defection was the entirety of Krieg, who, unlike their fellows, didn't leave their homeworld, but fortified it and soon conquered their entire system, making and keeping open trade routes with Old Cadia/The New Eye. Chaos Space Marines flocked to their worlds, either to help them or test their strength, but between the three forces, all Imperial attempts to dislodge this mini-Chaos Empire from their midst had failed, even with Astartes support or even Astartes leading the strikes.
In the other part of the Galaxy, Abaddon was not gloating. Imperial reports arrived stating that Abaddon had left in a hurry after completing the ritual, taken his ship to the Planet Killer and then fled the oncoming darkness, as it appeared not to wish to assist him, but devour him. If there was one silver lining in this debacle, it was at least that the Arch-Enemy's general would not profit from his foolish act either.
