The Nurthene Campaign was the Imperium's attempt to force the Imperial Compliance of Nurth, a former Terran colony that had devolved into a world with pre-industrial levels of technology during the Age of Strife. Originally fought by the Geno Five-Two Chiliad, a contingent of the Imperial Army and the Alpha Legion of the 670th Expeditionary Fleet, it would later be revealed that the mysterious Cabal played a major role in fighting the Chaos-tainted Nurthene.
The Desert World of Nurth was discovered during the Great Crusade by the 670th Expeditionary Fleet under the command of Lord Commander Teng Namitjira. Nurth was a lost human colony world. The population refused to accept the light of the Imperial Truth and opted not to join the Imperium of Man, resulting in a drawn-out, protracted Compliance campaign that would eventually result in the death of the entire world.
The Primarch Alpharius and a force from his XX Legion, the Alpha Legion, fought alongside the 670th Expedition during the tragic campaign to bring the world of Nurth to Imperial Compliance, but never became an official part of the 670th Expedition's order of battle. Lord Commander Namitjira remained in formal command during the operation, though of course he deferred to the Primarch's orders.
When first contacted by the Imperium, Nurth was a primitive, pre-industrial Desert World with geographic features fairly typical for such an arid environment. An exception to this was the harbour of Mon Lo, in the city of the same name. The harbour, while appearing perfectly natural to the ordinary onlooker, was actually an entirely artificial construction, having been created by the xenos organisation known as the Cabal some 11,826 Terran years before the arrival of Imperial forces on the world.
Before natural environmental changes had filled the harbour of Mon Lo with water, the bay had served as a giant landing pad or "waystation" for the Cabal's massive primary starship. As such, a detailed orbital scan of Mon Lo revealed features similar to that found on other worlds where Cabal waystations were built and the Cabal's mobile headquarters had come to rest for a time. Another location that featured unusual terrain was the town of Tel Khat, also known as Visages. The plain surrounding the town was littered with old, weathered sculptures of human heads, made from diorite and ranging in size from a pebble to a boulder. For unknown reasons, the ground of Nurth was coloured a striking combination of red and orange and the sky an unusually vibrant blue.
Nurth was eventually destroyed by the Nurthene themselves, as, on the verge of losing the war against the Imperial forces, the Echvehnurth, the Chaos-corrupted Nurthene military forces, activated a Chaotic weapon known as a Black Cube, an ancient weapon of planetary destruction created eons before by the first intelligent races of the galaxy. This weapon, through unknown means, transformed the climate of the planet, turning the air into noxious vapours utterly inimical to any form of life, and generating winds so strong that they scoured soil from the bedrock and raised the temperature to the point where the ocean boiled. In a matter of solar days, the process was complete, leaving Nurth a lifeless Dead World.
- Legion (Novel) by Dan Abnett