Salvation of Acheron

The Salvation of Acheron was a campaign that was a part of the larger Indomitus Crusade fought in the early decades of M42 against a large force of both Heretic Astartes warbands and legions of daemonic allies, following the formation of the Great Rift after the destruction of the fortress world of Cadia during the 13th Black Crusade in 999.M41, by the forces of Abaddon the Despoiler. This campaign took place in the Acheron System, the demesne of the bellicose and savage Imperius Ravagers Space Marine Chapter. They were later joined by the forces of the Indomitus Crusade, led by the resurrected Ultramarines Primarch Roboute Guilliman.

History
Following the destruction of Cadia by the Forces of Chaos during the 13th Black Crusade, the warp-riven galaxy is cracked asunder as the material universe and the Immaterium merge. A large tear in reality splits the galaxy in twain - from the Eye of Terror all the way towards the Eastern Fringe - forming the Great Rift. As the Noctis Aeterna sweeps over the northern reaches of the galaxy, cutting off the light of the Astronomican and all astrotelepathic communications, the northern half of the galaxy is all but isolated by the encroaching darkness, forming the Imperium Nihilus, or 'Dark Imperium'. With the waxing might of the Ruinous Powers, thousands of worlds are trapped within the Dark Imperium and are beset upon by the myriad enemies of the Emperor of Mankind, including the Forces of Chaos and xenos like the Tyranids, Orks and Drukhari. Surviving the destruction of the fortress world, the Imperius Ravagers are forced to withdraw. They make all haste towards the Acheron System, to defend their demesne from the encroaching tide of foul Chaos filth and their daemonic allies.

The ætheric storms of the Great Rift batter the worlds of the Acheron System, unleashing legions of daemons and various Chaos warbands of Heretic Astartes. The Imperius Ravagers and local Mesaran Mechanicus forces, fighting alongside the beleaguered forces of the local Astra Militarum regiments and local PDFs, dug in to stage desperate last stands against the encroaching Forces of Chaos. Hordes of traitors and abominations assailed the Imperial worlds of the Acheron System, as the Imperial defenders desperately struggled to hold the hordes of Chaos at bay. Large swathes of these worlds were ravaged by daemonic hordes as they slaughtered millions of innocents and offered their innocent souls to their dark masters. With the loss of over half their Chapter, the Imperius Ravagers bitterly fought against the endless legions of the damned, determined to sell themselves dearly and slaughter as many of the foul abominations as possible.

In their darkest hour, the Emperor answered the cries of His followers in the form of a newly arrived Imperial fleet entering the system. Though it had taken several decades for the Indomitus Crusade to reach this region of the galaxy, Primarch Guilliman and his Crusade fleet wasted no time in taking the fight to the Forces of Chaos. Like an avenging angel, the forces of the Indomitus Crusade struck like a thunderbolt, smashing the lines of the Chaos forces. After many more battles, the worlds of the Acheron System were finally cleared of the Chaos threat. With victory achieved, the various Imperial forces and worlds of the Acheron System sent delegations aboard the Lord Commander of the Imperium's flagship, the Macragge's Honour. Despite his extensive injuries, they were led by the Imperius Ravagers' Chapter Master, Legatus Praetore Thanatos Cronius, who was granted a short audience with his genesire. Painfully, the proud Chapter Master kneeled before the Primarch. When the Indomitus Crusade reached Charopós, it had brought a new breed of warrior with it.

The Ultramarines Primarch ha anticipated the need for such gene-bred heroes for this, the darkest age in the Imperium's history. He knew that the galaxy would eventually need warriors resilient enough to stand against the Forces of Chaos as the Imperium was poised on the brink of annihilation. Guilliman had learned of the Chapter's misfortune, and assigned over six hundred Primaris Space Marines to its reinforcement. The Imperius Ravagers' sorely depleted ranks were replenished nearly overnight. Legatus Praetore Cronius graciously accepted this profound gift from the resurrected Primarch and welcomed these new warriors into his Chapter's ranks.

Even as they continued the rebuilding of their shattered system, the Imperius Ravagers worked hard to bring their new Primaris brethren into the fold, teaching them the rites of battle and training alongside them night and day until the new warriors fought seamlessly with the old. Though a few traditionalists of the Chapter worried about inducting so many off-worlders into their ranks would change the soul of their Chapter, the new vision of the Imperium shared by their resurrected genesire and Chapter Master ensured that they kept their counsel to themselves.