Koloss Syntheticide

The Koloss Syntheticide was a massive campaign fought by the Imperium of Man against the rapacious machine forces of the Abominable Intelligence known as Koloss. This malign consciousness ruled over a swathe of systems known as the Obzen Apparatus, slowly conquering worlds and cleansing them of all organic life until the Imperium reached its borders. This was the last campaign of the Great Crusade in which the Emperor led His armies into battle.

The Syntheticide
On the cusp of the new millennium, a Mechanicum Explorator fleet encountered the Obzen Apparatus, an AI system which had devoted itself to the extirpation of organic life. Expanding slowly throughout the centuries of Old Night, the ruling intelligence known as Koloss carved out a small but powerful empire for itself.