A decade into the Sabbat Worlds Crusade, Warmaster Slaydo met his death in mortal combat with the Forces of Chaos on the world of Balhaut in 765.M41. Before dying, Slaydo passed on command of the Crusade to a junior officer of some renown, Marshal Macaroth. Considered one of the few blind spots of the new Warmaster, Macaroth had a tendency to put his faith in a cadre of newly minted officers. He fully expected those junior officers that had been fast-tracked into command to display the same innovative and innate abilities to command that he possessed. During the Crusade's thrust into the Cabal Systems, these new Imperial commanders made several gross miscalculations. General Urienz proved to be the exception as he helped the Crusade achieve a string of successful victories within the Newfound Trailing and Khan Groups.
One of Urienz's most celebrated victories occurred on Nyzon II in 768.M41 when he faced the Chaotic forces under the command of the Magister Rusheck Vakkim. Urienz's forces were conducting a line of advance towards Alpha Madrigo when his attached Imperial Navy reconnaissance squadrons identified Magister Vakkim's fleet riding at high anchor above Nyzon II. Urienz immediately ordered his fleet to engage the Chaotic warships, taking the Magister unaware. The orbital battle swiftly turned into a bloody ship-to-ship boarding action. General Urienz personally led the boarding action of Vakkim's own warship, the Crown of Thorns, and proceeded to heroically capture Vakkim. The Magister later escaped Imperial captivity through some unknown means which has never been fully explained. Vakkim and nine of his G'uttkhra managed fled to the planet's surface, but were hunted down by an Imperial Kill-team two days later. Led by Urienz's brilliant protege, Commander Lang Mowzer, the Vakkim and his subordinates were eventually cornered at Penetor Hive and exterminated during a vicious fire-fight.
As the Imperial Crusade pushed further into the Cabal Systems, Warmaster Macaroth overextended the reach of his forces, making himself vulnerable on three sides. The new Archon of the Forces of Chaos in the sector, Urlock Gaur, sought to exploit this vulnerability to the fullest, and led a series of counter-strikes against the forces of the Crusade. Macaroth quickly redeployed elements of his spinward flank, in a last-ditch effort to reopen the Crusade's supply lines. General Urienz was placed in command of the Crusade's 4th Army to achieve this objective. His primary target was the world of Ariadne and its solid fuel reserves. Between 771.M41 and the middle of 772.M41, Urienz conducted several improvised and often desperate operations to secure this target world and help keep the Crusade alive.
- Sabbat Worlds Crusade (Background Book), pp. 66-67, 69-71