The Knights of Guilliman are a Loyalist Chapter of Novamarines descent and through them the Ultramarines. As expected from those of the Roboute Guilliman's blood, they are staunch adherents to the Codex Astartes and are often at odds with those that scorn it. Their homeworld is a feudal world very similar to the ancient Dark Angels' homeworld; Caliban. They are currently on a penitent crusade for siding with the Secessionists during the war known as the Centurion War. The Centurion War was fought in late M41 between the forces of the Imperium and Adeptus Mechanicus Secessionist forces under the rule of Magos Atilla who seized control over several Forge Worlds and led an attempt to secede from the Imperium.