Penitent Crusade of Vengeance

The Penitent Crusade of Vengeance was a penitent crusade carried out by the Blades of Dorn Space Marine Chapter during the early centuries of M38. Following the excommunication of their genetic forebears, the Crusaders of Dorn after the events of the lamentable Abyssal Crusade, doubt and suspicion was cast upon their descendant Chapter, the Blades of Dorn as well. Refusing to be labeled as traitors, the Blades of Dorn took an Oath of Moment, and vowed to undertake a penitent crusade deep into the hellish realms of the Eye of Terror itself. They would prove, beyond a shadow of a doubt, their loyalty and unshakeable resolve to both the Imperium and the God-Emperor Himself. After nearly eight decades had gone by, the sorely depleted Chapter returned to the realms of man and were tested, body and soul, by agents of the Inquisition. Their genetic forebears, the ancient and stoic Imperial Fists vouched for their cousin Chapter, and having passed every soul-crushing test thrown at them, they were absolved of their forebears' sins and granted the Emperor's forgiveness.

History
When the Blades of Dorn's genetic forbears, the Crusaders of Dorn, are deemed Excommunicate Traitoris following the events of the Abyssal Crusade in 112.M38, suspicion and doubt fall upon their progeny as well. Despite having their integrity and loyalty brutally tested by the Imperial Fists themselves, this is not deemed a good enough reason to allay the suspicions of the Ordo Hereticus. Therefore, the Inquisition forces the Blades of Dorn to undertake a penitent crusade into the Eye of Terror itself. Should they successfully prosecute this nigh-suicidal task, and emerge uncorrupted from this hellish realm, they would be deemed loyal and saved in the eyes of the Emperor. With no other recourse, the Blades of Dorn set course for the Cadian Gate, and then disappeared into the hellish realm of the Eye of Terror.

Nearly eight decades later, the battered Blades of Dorn Chapter fleet once again reemerged into realspace near the Fortress World of Cadia. They were reunited with the Imperial Fists and granted an audience aboard their star fort Phalanx. They were detained and thoroughly tested by the agents of the Inquisition, both in body, mind and soul, and were not found wanting. Satisfied, the Inquisition absolved the Blades of Dorn Chapter of their progenitor's sins and granted them the Emperor's forgiveness.

The Blades had successfully purged more than two dozen worlds within the Eye, but had lost nearly half their number in the process. To help assist them in rebuilding their shattered ranks, the Imperial Fists granted them some of their own genetic stock. This was both symbolic as well as practical, as the Blades would now receive the purest of Dorn's bloodlines, which would help tie them closer to their genetic forebears, as well as absolve them of the tainted gene-seed of their corrupted progenitors. The Imperial Fists also provided some of their most ancient relics, arms and equipment to help rebuild the fighting strength of the newly absolved Chapter.