Though the reach of the magos dominus’ mightiest engines stopped at the brute-shield, they were not without impact. The nobles of the Knight Houses had long sworn fealty to Mars, and on the battlefields of Ullanor they adhered to those ancient oaths through the fiercest fighting.
A dozen metres tall, the ancient walkers of the Knight Scions stalked the ruins of Gorkogrod seeking the enemy wherever they could be found. Unhindered by the broken terrain, the massive Knight suits pushed forward where tanks could not, carving into the enemy and laying waste to the city itself.
Knights Paladin led the line, their battle cannons breaking ork mobs as easily as they crumpled the armour of tanks and transports. Chainswords several metres long were more than a match for the claws and buzzsaws of ork heavy dreadnoughts and mega-armoured nobles. With the Paladins came Knights Errant with thermal cannons to vaporise metal and flesh, the flanks of their squadrons secured by darting forays by paired Knights Lancer.
Directional ion fields crackling under incessant barrages from ork artillery and tank guns, the towering Knights Castellan and Crusader were bastions around which the infantry of the Adeptus Mechanicus could hinge their attacks. Battle servitors and carapace-suited skitarii flooded the ruins, a wall of red every bit as relentless as the ork waves that crashed against them.
The Great Beast showed its cunning here also, harbouring its forces well, committing them only when needed. Where the Knights strode, infantry and light vehicles attempted to speed past to strike into the rear of the advancing Cult Mechanicus. Where the Knights were not, the weight of battlefortresses and super-heavy stompers — war engines a match for any Imperial Knight in bulk and firepower — was pressed hardest. But no amount of raw strategy could guard against the meticulous encroachment of the Martian warriors, guided by machine intelligences and the most sophisticated battle-augurs.
Zhokuv wielded the men, servitors, tanks, automata and war engines like an overseer of a manufactory, driving them on hard but weighing every loss against potential gains, seeking efficiencies with ruthless precision. Like the gears of a machine the Martian army continued to grind on. Sometimes the Mechanicus overpowered the orks through sheer force of guns, machines and men. At other times they used superior logistics to draw the greenskins into ambushes or outpace them with rapid flank attacks that cut them off from their support coming from the inner city.
Block by block, street by street, the Adeptus Mechanicus took Gorkogrod, until the lead echelons of Kataphron cyborgs and Praetorian heavy servitors were a kilometre inside the brute-shield. Thousands of Martian veterans swarmed forward to occupy abandoned bunkers, while tech-priests and magi seized and analysed what they could of the ork technology in the hopes of discerning some secret of how the brute-shield worked or was powered.
Much to the dismay of his less bellicose advisors, Zhokuv left the command headquarters protected by the Warlord Titans and sought to view the new front line in person. Escorted by Knights Warden and Knights Castigator of House Taranis, the dominus sallied forth in his battle shell.
Riding behind in a tracked armoured car, Laurentis and others of the inner cadre looked in awe at the devastation that had been brought to Gorkogrod. Of the city they had seen on the initial scans and vid-streams, only the inner reaches remained. The mountainside was littered with ruins and the remnants of war engines both human and ork. Shell craters were criss-crossed by seared trenches from volcano cannons, marked by glassy bowls of plasma detonations.