First Pacification of Luna
|Imperium||Gene-Cults of Luna|
| VII Legion
|Unknown, presumably light to moderate||Unknown, presumably heavy|
The First Pacification of Luna saw the complete subjugation of Terra's moon, Luna, by the early Legiones Astartes. The first true battle of the Great Crusade, the subjugation of Luna allowed the Emperor to use its advanced genetics facilities to mass-produce His Space Marines.
Being the first battle the Legiones Astartes fought outside of Terran skies, it was launched while the Unification Wars on Earth itself were still coming to a conclusion. The forces of the Emperor had already made great headway on Luna's surface, though the forces of the stubborn Cardinal Tang still held a number of fortress zones and enclaves. Tang himself commanded the gene-cults of Luna, those who believed that human nature was fractal, fractured, and transcendent. To them, the true nature of mankind was visible in the flesh and mind of the individual, but that each person was an echo of archetypes that persisted throughout human existence. Each cult clung to a different set of archetypes: some represented as anthropomorphic figures, some as numbers, and some simply as symbols. These fanatical cults were nonetheless capable gene-forgers and geneticists who operated out of massive subterranean laboratories the Emperor coveted for His own plan to mass produce His Adeptus Astartes.
After refusing to subdue and control the gene-cults diplomatically, the Emperor turned to a military option. The final straw came when the gene-cults returned one of the Emperor's emissaries as a still-screaming soup of fused flesh and metal. The Emperor deployed three Space Marine Legions, VII Legion, XIII Legion, and XVI Legion, each far smaller than it would be during the Great Crusade.
Legion XVI acted as the force's vanguard, launching itself towards Luna from Earth-based rockets. Behind them came smaller waves from the VIIth and XIIIth Legions. The formidable ground based defenses on the surface of Luna controlled by the gene-cults opened fire. The Emperor used Legions VII and XIII as distractions, allowing Legion XVI to land assault craft unnoticed. The Astartes quickly moved into the gene-cults underground complexes, battling half-machine genetic monstrosities. These initial positions fell within seconds, with the hundred or so cultists inside dead before even realizing they were under direct assault. The Astartes disabled the cultists' orbital defenses from inside, allowing Legions VII and XIII to land and begin a systematic annihilation of all their remaining resistance. The battle only lasted six hours before all resistance on Luna crumbled. The surviving gene-cultists surrendered, begging that the Emperor "call off his wolves". The now-humbled gene-crafters of Luna would be granted mercy, but were enslaved by the Emperor for His own plans.