The Selenar, also called the Selenite gene-cults, were a group of religious cultists settled on Luna, the moon of Terra, who possessed some of the most advanced genetic engineering technology in the human-settled galaxy during the Great Crusade and Horus Heresy eras.
The Selenar were divided up among several different cults which sought to use potent genetic engineering techniques they had developed to resurrect their cultists through multiple lives in the hopes of ultimately creating the perfect expression of each of several different human archetypes they had identified.
The Selenar were conquered by the early Space Marine Legions during the First Pacification of Luna in ca. 798.M30, and would go on to use their technology to help the Imperium of Man accelerate the development of new Astartes for the Legions during the Great Crusade.
However, the Selenar never came to terms with being conquered by the Imperium, and mounted several notable instances of rebellion against Imperial rule before their last remnants were destroyed following the end of the Horus Heresy.
First Pacification of Luna
This early Imperial campaign was the first operation mounted by elements of the early Space Marine Legions beyond the skies of Terra. The Unification Wars were still raging across the surface of Mankind's birth world at this time.
Luna was the bastion of a conglomeration of resurrectionist gene-cults whose members believed that human nature was both fractal, fractured and transcendent. Each of these Selenar gene-cults clung to a different set of archetypes. Every cult member was a product of creation by the Selenar gene-wrights according to formulae crafted in the Dark Age of Technology. Resurrected in body time and time again they sought to distill the true personification of a single human archetype.
In their subterranean complexes the cults were powerful, insular and resistant to the Imperial Truth. The Imperials would have normally dealt with these insular cults in the usual matter they handled all of the other Terran factions and techno-barbarian states that refused to accept the rule of the Emperor of Mankind -- by obliteration.
The fact that the Selenar gene-cults had something that the growing Imperium needed complicated that position. The Selenar returned the Imperial entreaties for alliance with silence. As the threats of the Imperium soon began to outnumber its offers, the Selenar cults began to gird themselves for war.
So it was that the Emperor finally ordered Luna to be pacified by the sword, their superstitious beliefs cast down before the Imperial Truth and their gene-craft yoked to the needs of the Imperium. To this task the Emperor set the three of His newborn Space Marine Legions most suited to this purpose on what some Imperial chroniclers name as the first true battle of the Great Crusade.
The combined force of the VIIth, XIIIth and XVIth Legions (later named the Imperial Fists, Ultramarines and Luna Wolves) lifted from the surface of Terra in a scattering of rocket flame. The as yet unnamed XVIth Legion had been chosen to serve as the Space Marine force's vanguard, and had brought its full strength to bear. Cutting power to their assault craft, the Astartes of the XVIth Legion drifted silently towards Luna through the void like arrows fired into the night.
As the smaller wave of assault craft belonging to the VIIth and XIIIth Legions approached the airless world, the Selenar defensive weapon systems embedded in Luna's surface lashed the oncoming Imperial force. The XVIth Legion's assault craft, unlooked for and unseen, struck their targets like a dagger in the night.
Within six solar hours of the first shot being fired, Luna had been pacified and brought into Imperial Compliance, the first off-world conquest of the Imperium of Man. Faced with annihilation, the surviving Selenar cultists bent the knee instead, their surrender communique transmitted to Terra calling for the Emperor to "call off his wolves."
Broken and humbled, the enslaved gene-wrights of Luna would help forge the next generation of Space Marine who would carry out Mankind's conquest of the stars. As for the XVIth Legion, they had earned their name -- the Luna Wolves.
Always resentful of their conquest by the Imperium and the use of their technology for the Emperor's purposes, the Selenar engaged in an act of shocking sabotage during the Great Crusade. They engineered a virus that infected and destroyed much of the gene-seed stocks of the IIIrd Legion.
However, the IIIrd Legion's numbers were so reduced by the disease that the renamed Emperor's Children were forced to fight for many solar decades alongside the Primarch Horus and his Luna Wolves until their numbers could be replenished with new gene-seed derived from the Primarch's genome.
At some unknown point, it is known that the Selenite gene-cults were ultimately purged by the Imperium due to their rebellious behaviour, but at least some elements remained on Luna and still possessed their genetic engineering technology at the time of the Solar War during the Horus Heresy.
Shortly before the Siege of Terra began, during the storming of Luna by the Sons of Horus forces under the command of First Captain Ezekyle Abaddon, the leader of the surviving Selenar cultists, the Matriarch Heliosa-78, refused to carry out her orders from Rogal Dorn, the Praetorian of Terra, to destroy her genetic engineering technology in order to prevent it from falling into the hands of the Traitor Legions.
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