While on Tuva Chaos forces were retreating ate breakneck speed, and Maybourne was being liberated, the Catechism was concentrating on the Orks. Its best units were thrown against Nazghat's remaining forces, forcing the front line back towards the Ork landing zones. Then, at the appointed moment the daemons were released. The gibbering, capering monstrosities tore through the Ork lines before materialising amongst or even behind the greenskins' defences. In a very short period, less than a day, the Ork line, which had held strong for weeks against the best of the Catechism's troops, collpased catastrophically once they realised their leader and his best Nobz had "skarpered" to invade elsewhere.
By the end of 1212.008M42 the Orks had fallen back to their crashed Rok's which made up their landing zone, and were desperately trying to work out how to get off the planet!