The Ullanor Crusade

At the height of the Great Crusade, humanity's armies faced their sternest test yet in the sprawling greenskin empire of Ullanor. The Ullanor Crusade was a war on a scale the galaxy had rarely witnessed, pitting the full might of the Space Marines and the Imperial Army against the teeming hordes of the Ork Overlord Urrlak Urruk.

The campaign was brutal and prolonged, for the greenskins bred faster than they could be slain. Yet under the masterful command of Horus Lupercal, the Imperial forces struck at the heart of the Orks empire, cornering the Overlord and his warband in a decapitating assault that shattered the xenos war-machine. The victory was absolute, a testament to the Emperor's vision of a united and reconquered galaxy.

Upon the dusty plains of Ullanor, before assembled Legions beyond counting, the Emperor named Horus the first Warmaster and gave His favoured son command of the Great Crusade in His stead, before departing for Terra. It was the zenith of the Imperium's golden age, a moment of unmatched glory. None who cheered that day could have known that the honour bestowed at Ullanor would sow the seed of the galaxy's greatest betrayal.