The Triumph of Ullanor was the greatest celebration of the Great Crusade, a vast victory parade held upon the conquered greenskin world of Ullanor to mark the breaking of a monstrous xenos empire. Millions of soldiers, war-machines and Space Marines assembled beneath the gaze of the Emperor Himself, the culmination of two centuries of relentless conquest.
It was here that the Emperor chose to depart the Crusade and return to Terra, and here that He named Horus as Warmaster, elevating His favoured son above all other Primarchs to command the war-effort in His absence. The honour was as much a burden as a glory, sowing seeds of pride, isolation and envy that would ripen into ruin.
For the Sons of Horus the Triumph was the zenith of their gene-father's ascent. Yet in the eyes of many chroniclers it marked the beginning of the end, the moment the seeds of the coming Heresy were quietly sown.