Battle for Wahrheit

The Battle for Wahrheit was an Imperial campaign undertaken by the Shadow Phantoms Space Marine Chapter against the Imperial world of Wahrheit that had fallen into strife and open insurrection. The Chapter was dispatched to quell the rebellious elements of the population and bring a modicum of security to innocent civilians. When the heretic forces received further reinforcements in the form of mutants and Chaos-corrupted Planetary Defence Forces and Chaos Cultists, their vast numbers threatened to overwhelm the Space Marines through attrition. The outnumbered Shadow Phantoms received salvation in the form of the newly arrived Zero Legion, their suspected Primogenitors.

History
The Dark Core Chaos Space Marines began their assault with swift ruthlessness, slaughtering the Space Marines sent to quell the rioting, along with the PDF with them and nearby civilians. Under the command of the Specters and Chaos Cultists, dissension and anarchy was spread across the planet, leading mutants and corrupted PDF and Hive Gangs against the defenders. The Shadow Knights were having difficulties in repelling the invaders, and several of their companies had to be recalled from present campaigns to assist in the homworld's defense. The conflict took over half a year, and the Dark Core were utilizing their usual tactics of sowing treachery and inner-conflicts among the populace, greatly reducing the Shadow Knight's efforts in reclaiming the planet and bringing order.

Salvation came in the form of three Divisions of the Zero Legion, the long suspected ancestral chapter of the Shadow Knights. Having seen the tactics of the Dark Core in previous campaigns, the Zero Legionaries were able to assist the defenders in repelling the Chaos Space Marines, and bringing back order to Wahrheit. The psykers of both chapters worked together to close the warp gates down in the under parts of the Hive Cities, while the rest of their forces, along with Imperial Guardsmen and PDF hunted down any surviving Chaos Space Marines and Cultists.