A Brief History of The Exorcists

“The Emperor’s Light Compels You!”

The origins of the Exorcists chapter of the Adeptus Astartes can be traced back to the birth of the Primaris legions and the early days of the Indomitus Crusade.  The chapter began as a detachment of Greyshields led by Captain Gulielmus Petrus.  They served in the expeditionary fleet led by Roboute Guilliman, Lord Commander of the Imperium.  The detachment fought in several engagements alongside Guilliman himself, learning the ways of the Codex Astartes directly from its author.

As the years went on, Captain Petrus and his company began to see Guilliman as a divine being, second only to the Holy God Emperor on Terra.  Knowing that the primarch was staunchly opposed to the Ecclesiarchy and the religious fervor that had dominated the Imperium during the ten thousand years of his absence, they kept this reverence secret.  Eventually, Guilliman became aware of their secret faith.  He would have chastised Petrus and his men, but he could see that the religious devotion was not unique to this company, and he had little time to spare for such distractions.  Thus he grudgingly tolerated their worship. 

As the end of the first phase of the Indomitus Crusade drew to a close, Guilliman dispatched the Primaris throughout the Imperium Sanctus.  Some went to reinforce existing chapters, others to form new chapters of their own in defense of the myriad human worlds under constant threat from Xenos and Chaos factions.  Captain Petrus’ company was sent to bolster the defenses of 40 Gemini, a shrine world on the edge of the Cicatrix Maledictum near the Nachmund Gauntlet.

40 Gemini was besieged by Chaos Demons spewing forth from a warp rift close to the planet.  The imperial forces in the system were all but overrun when Captain Petrus and his Greyshields arrived.  The Primaris marines were a boon to the remaining defenders, but it still took nearly a decade to expunge the demons from the planet.  Captain Petrus rebuilt the stronghold at the shrine of Saint Regan and made it the home of the newly named Exorcists, where he assumed the title of Chapter Master.  He replenished the chapter’s strength by drawing recruits from the remaining imperial citizens, a deeply religious people whose devotion to the Imperial creed was emboldened by the arrival of the Emperor’s Angels.

The Exorcists adhere closely to the Codex Astartes.  They deploy a combined arms approach to battle, though they specialize in infantry tactics.  They favor bolter weaponry, which they wield as holy icons.  Bolt ammunition is sanctified with holy water and inscribed with prayers to the Emperor.  In combat, they dispense the Emperor’s absolution through punishing volleys of bolter fire.  

It is speculated by some that their trait of deep religious faith is a byproduct of the genetic manipulations of Archmagos Dominus Belisarius Cawl during his creation of the Primaris legions, and that the gene seed of these particular Primaris marines includes some genetic material from Lorgar of the Word Bearers.  Though they are now more open about their religious devotions, this suspicion is only held by the highest ranking members of the chapter and remains a closely guarded secret.