As the Great Crusade continued the expansion of the nascent Imperium across the galaxy, the discovery of the Primarchs and their newly adopted homeworlds helped to stem an impending crisis that was not widely known of at the time outside of the exalted ranks of the Imperium's ruling War Council: namely, the diminishing stability of the Astartes' gene-seed itself through over-use and the increasing need of the Imperium for ever greater numbers of Space Marines in the field. This was a matter that was only exacerbated as the Expeditionary Fleets of the Great Crusade pushed ever wider afield into the galaxy. Imperial forces could no longer be concentrated as easily as before, and attrition was taking its toll as the years of near-constant battle became decades. Slowing the pace of the Great C