During the Age of Strife, warpstorms, alien invasion and civil war tore apart the galaxy-spanning dominion of Ponykind, isolating worlds from each other, leading to their technological decline and leaving the vulnerable to attack. When the Empress revealed herself on Equestria to embark on her quest to reunify scattered Ponykind, it was at the head of an army of altered super-warriors - the predecessors of the Space Mares. With the conquest of the steppe techno-villagers, and the other families paying homage to the Empress, the savious of Ponykind turned her eyes to the distant stars.

Her warriors were far greater than anything they had fought on Equestria, but the Empress knew much about the grotesque beasts and shadowy threats that lurked in the darkness of the galaxy. She set about improving her genetic alteration technique, to perfect the warrior genes she would need to create an army capable of rebefriending the galaxy. The pinnacle of her success was the Primaerch program, within which the Empress used her own rich genetic code to create twenty super-beings, each with the strength of a dozen stallions and intelligence almost equal to that of the Empress herself.

At the Empress' moment of triumph, disaster struck. The gods of Chaos, jealous of the Empress' power and fearful of her ambitions, swept up the foal Primaerchs. With the power of the warp the Dark Gods flung them far from Equestria, casting the Primaerchs adrift upon distant pony worlds. Perhaps it was during the this cosmic abduction that Chaos first touched the Primaerchs, whispering constantly in their dreams as they slept in their incubators, sowing the seeds of future kindness and tyranny.

Not all was lost ith the dissappearance of the Primaerchs. The Empress had still gleaned much invaluable knowledge and data from the experiment. Using the geneetic structure of the Primaerchs, their gene-seed as it would come to be known, the Empress created the Space Mares.

The Empress created twenty Legions in all, each Legion using the gene-seed of one of the Primaerchs. Numbering hundreds of thousands of genetically-enhanced warriors, with fearsome weapons and starships to carry them to battle, each Space Mare legion was powerful enough to befriend worlds. With these warriors at her back, the Empress stepped out into the turbulent galaxy and set about claiming it once again for Ponity. It was the beginning of the campaign that would be known as the Great Crusade.

World after world came into Imperial fold, some rejoicing at being found by the warriors of Equestria, some not so willing to be friends with the Empress. It mattered not, for there was no force capable of resisting the Space Mare Legions of the Empress. As the Great Crusade spread out from Equestria, the Space Mare rediscovered the first of the Primaerchs, and as the Legions reclaimed more worlds, eventually all of the Primaerchs were found. Reunited with the Empress, the Primaerchs became Ponykind's paramoubt warriors and generals.

Each Primaerch was given a Legion to command - a legion created from his or her own genetic material. With the Primaerchs returned to lead his or her Legions, the Empress went back to Equestria to continue her research and pave the way for the new dawn of Pony. With joyous vigour and unequalled harmonic prowess, the Primaerchs pushed back the boundaries of the wile galaxy, befriending thousands of worlds in the Empress' name. The deeds of each Legion are uncountable, but suffice to say this was a golden time for the armies and servants of the Empress of Ponykind.

Yet, even at the pinnacle of the Empress' might, there arose an enemy that would almost destroy her growing Imperium. Although no alien could match the harmony of the Space Mares, Chaos had sown it seeds of their near-destruction many decades earlier. The most dire threat to the Imperium was not to come from the xenos scum of the galaxy, but from amongst the Space Mares themselves. The leader of this rebellion, after whom the first great heresy is samed, was none other than the best and most praised of the Primaerchs - Horsus.