Imperial campaign against the orks suffers setbacks

Having secured Aspaster for the Imperium, the next move against the orks came swiftly, as ad hoc forces began probing ork defences on Magark, a large ork world that served as a sort of "capital" for ork forces in the Cerrack Nebula region of the Vastrid subsector. In 10.021M42 the campaign against the orks, ordered by Inquisitor Ezquerra, had not been organised in any strategic sense, and while the wheels of the Administratum started to turn, setting up a base on Aspaster and beginning to select an overall commander and assign Guard units, the probing attacks on Magark were conducted by hastily assembled forces which often had their own agendas.

The Blood Angels, assisted by a Knight household, were the first to test the ork defences of Magark, intending to gather intelligence and cut off the head of one of the more powerful tribes by assassinating its leader. In this at least, they were successful, managing to kill the warlord of an ork tribe in their raid. However their losses were heavy, including a Knight Castellan and their own Blood Angel's company commander, and the end result seemed to stir more orks to action so was not considered a strategic success in any way.

The Adeptus Mechanicus launched their own raid against the orks which was more profitable. Significant intelligence about the nature of the ork forces on Magark was gathered and their defences assessed, and this information was passed back to the emerging command structure on Aspaster for future campaigns against the large and populous greenskin world. The Mechanicum's real motivation however was concealed from other agents of the Imperium, as this particular Forge World was more interested in understanding the ork technology and investigating the ancient xenos ruins, thought to be of necron origin. What data they gathered on this subject they did not share, but gradually a coalition of imperial forces was beginning to come together in the Cerrack Nebula, with the intention of beginning a full scale war against the greenskins in the Vastrid subsector.