Luna

Luna is the traditional name for the Moon of Terra which the Imperium of Man classifies as both a Dead World and a Civilised World that is home to billions of people in hive cities built below the surface of the lunar regolith. Humans first landed on Luna in the year 969.M2, making it the first world ever explored by Mankind in the ancient past. In the subsequent centuries it was one of the first worlds colonised by humanity, who erected great domed cities above and below its airless surface. Luna became a center of scientific research and zero-gravity manufacturing during the Dark Age of Technology, when it became the home of the Selenar gene-cults who saw the perfection of advanced genetic enginnering techniques as a necessary part of a religion similar in some ways to that of the Cult Mechanicus of the Mechanicum of Mars. The Emperor of Mankind conquered and united Old Earth during the Unification Wars following the Age of Strife in the 30th Millennium and then sent his forces to occupy the human colonies on Luna. It was in the lunar gene-laboratories that the Emperor began the Primarch Project, the massive genetic engineering research initiative necessary to create the Primarchs from his own genome, though their actual gestation was carried out in his secret gene-laboratories beneath the Himalayan Mountains to provide greater protection from the interference of the Dark Gods of Chaos. Unfortunately, these arcane protections ultimately proved inadequate and the Primarchs, still developing infants locked into their gestation capsules, were scattered across the galaxy after the Ruinous Powers opened a Warp Rift within the Imperial laboratories. Yet from the Primarchs' remaining genetic material the Emperor was able to create the first Space Marine Legions, using the organs cultured from the Primarchs' gene-seed to transform ordinary human men into superhuman warriors.

History
By the end of the Age of Strife, Luna had become a bastion of a conglomeration of resurrectionist gene-cults, the members of these cults believing that human nature was both 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 them as anthropomorphic figures, some as numbers, and some as symbolic systems. Shot through with low occultism, most fell short of deification, but all pursued understanding through their craft of gene-forging. Each cult member was a product not of random breeding, but creation by the cult gene-wrights according to formulae born in the Dark Age of Technology. Resurrected in body time and time again they attempted to reach a true personification of a single archetype. In their subterranean complexes the cults were powerful, insular and resistant to the Imperial Truth. Such resistance was hardly a novelty, and would normally have been dealt with in the usual manner -- by obliteration. The fact that the gene-cults had something that the growing Imperium needed complicated that position.

Clouded as it might have been by occultism, the gene-craft of the Selenar Luna cults was unequalled save within the Emperor's own facilities on Terra. With Terra teetering on the edge of complete unification, the conquest of the Sol System and the galaxy beckoned. For the Great Crusade there would need to be more and more Space Marines. The Terran facilities would not be able to cope with such a huge increase in the creation of recruits for the Legions, so the Imperium needed Luna's wealth of gene-craft and capacity added to its own. But the Selenar gene-cults would not bow willingly to the hunger of the new-born Imperium, and had fought off the machinations of Terran warlords and Martian magos in the past. The Selenar had received Imperial ambassadors with courtesy, but answered their offers, threats and entreaties with silence. As the threats began to outnumber the offers the Luna cults began to turn away the ambassadors and gird themselves for war. Normally highly factional, the possibility of Terran domination overcame all doctrinal disagreements between the cult matriarchs and gene-wrights -- they would resist the Imperium together and without limit. The final Imperial deputation to Luna was returned to Terra as a still-screaming soup of fused liquescent flesh in the dead shell of their shuttle. 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 As such, Luna would become the site of the first off-world Imperial Compliance action ever taken by the early Astartes Legions, even while the Unifications Wars were still raging on Terra before the year 800.M30.

First Pacification of Luna
To the task of conquering Luna the Emperor set 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 VII, XIII and XVI 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 XVI Legion had been chosen to serve as this Space Marine force's vanguard, and had brought its full strength to bear. Cutting power to their assault craft, the Astartes of the XVI Legion drifted silently towards Luna from Mankind's birthworld through the void like arrows fired into the night. As the smaller wave of assault craft belonging to the VII and XIII Legions approached the airless world, the Selenar defensive weapon systems embedded in Luna's surface lashed the oncoming Imperial force. The XVI Legion's assault craft, unlooked for and unseen, struck their targets like a dagger in the night. Within six 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 XVI Legion, they had earned their name -- the Luna Wolves.

Luna's Strategic Importance
Luna is home to immense planetary defence lasers charged with protecting Terra from invasion. These defences inflicted savage losses on the invading Traitor Legion fleets of the Warmaster Horus during the latter stages of the Horus Heresy.

Luna Naval Base
Luna was the home to the greatest naval base in the Imperium of Man at the time of the Great Crusade and the Horus Heresy. Luna also gave its name to the most common class of Imperial Navy Cruiser, the Lunar-class.