During the Third War for Armageddon in 998.M41, the Noctan Strike Forces used their incredible skills at infiltration and night raiding to hinder occupying Ork forces primarily around the captured Acheron Hive wherever possible. When it became clear that Acheron would fall to the Ork advance, Colonel Walde, leading the 29th Noctan Strike Force, ordered three of his companies to infiltrate the hive city. Tasked with leading a guerrilla war against the marauding Orks, the brave men of these companies buried themselves deep within the labyrinthine tunnels of Acheron's undercity to escape detection and organise the human survivors of the Orks' attack into a solid resistance force.