The Siege of Vraks was one of the longest and most gruelling campaigns of the entire 41st Millennium, a seventeen-year ordeal fought to reclaim a single world from the grip of heresy. Vraks Prime was an Imperial armoury planet, its endless bunkers packed with enough munitions to arm a whole crusade, and when its Cardinal fell to apostasy the Imperium could not for a moment allow such an arsenal to remain in the hands of traitors.
The grim task fell to the Death Korps of Krieg, soldiers bred for exactly this kind of attritional nightmare and willing to spend their own lives without hesitation or complaint. They landed millions of men to besiege a heavily fortified world defended by a swollen apostate garrison, and the war swiftly settled into the very horror the Korps understood best: endless trench lines, thunderous artillery barrages and grinding assaults across a cratered and corpse-strewn no-man's-land.
As the years dragged on without end, the defenders sank ever deeper into damnation, their leaders binding themselves body and soul to Chaos and drawing renegade Astartes and gibbering daemons to their doomed cause. The fighting descended at last into the tunnels beneath the surface, a lightless war of grenade, flamer and bayonet fought for scraps of ruined ground, with total casualties eventually climbing into the millions on both sides. Whole generations of Krieg soldiers were born, armed and expended in those trenches without ever once seeing the surface.
At the bitter last the Death Korps ground the heretics down and reclaimed the world, but the prize was a poisoned and shattered wasteland strewn with the dead and steeped in the residue of Chaos, fit only to be quarantined and forgotten. The endurance of the Krieg is chronicled further in the account of the planet of Krieg.