Astartes battle orks on Mezria VI

On Mezria VI both the orks and Imperium were gradually building up forces as the battle for the world became an all out war between the two opposing sides. By 04.022M42 the Bloodfang tribe had landed several greenskin armies, but the Imperium were still in the process of building up their forces. The main participants in this phase of the Mezria VI campaign were astartes chapters, and the Dark Angels and Hammers of the Emperor had sent almost a company each of the elite superhuman troops.

There wasn't exactly a "front line" on the planet as such, given the vast distances involved and the small size of the participating forces. Instead the orks persistently sent out roving patrol forces, which would then clash with whatever enemy they found. Initially this caused problems for the Imperium, as the Dark Angels were caught by surprise in the open on 2204.022M42. Barely any of the astartes survived, and it was a lesson for the Imperium. The strategy changed to using scouts and Adeptus Mechanicus scans of the surface to identify ork forces and their movements.

The Hammers of the Emperor took full advantage of this a few days later, identifying a large mob of orks which appeared to be centred around important orks that may be HQ or leader elements. The Hammers drove directly into the mass of greenskins, taking out these key targets, before withstanding the inevitable onslaught as the giant horde of angry orks charges the marines. The Hammers held on long enough to be evacuated, and their objectives had been met. As the Hammers of the Emperor withdrew to the relative safety of the almost complete imperial bases, the orks devolved into fighting with one another now that their leaders had been assassinated. The war on Mezria VI was not over however, as the greenskins roamed unchallenged across half the planet, though the construction of imperial bases was now well underway.