It was while Horus made his plans for what would become known as the infamous Drop Site Massacre on Istvaan V, that the Warmaster sent word to the XVIIth Legion’s Primarch Lorgar that the time had come for his Astartes, the Word Bearers, to strike against the Imperium. The Warmaster was keenly aware of the bitter hatred that Lorgar had for his Primarch brother Roboute Guilliman and his XIIIth Legion, the Ultramarines, who had once humiliated the Word Bearers by destroying their city of Monarchia on the world of Khur at the Emperor's orders during the Great Crusade. Horus told Lorgar that he had fed Guilliman false intelligence in regard to a possible threat in the Segmentum Tempestus, far to the galactic south of Terra that stemmed from the Orks of the Ghaslakh Empire. Horus had ordered th