“We follow in the footsteps of Guilliman. As it is written in the Codex, so shall it be.”
–Marneus Calgar, Chapter Master of the Ultramarines
Of all the thousand and more Space Marine Chapters,it is the blue-clad Ultramarines that, in the mind
of the countless billions of the Emperor’s subjects, personify everything that the Adeptus Astartes stands for. The Ultramarines and their many successor Chapters have stood at the very forefront of the war against the traitor, the alien, and the fiend since the very foundation of the Imperium. Across
the domains of the Emperor, the Ultramarines are celebrated as heroic, virtuous, and noble defenders of Humanity, their deeds celebrated in devotional works the length and breadth of the galaxy.
Unusually for the Astartes they control entire star systems, in a realm known as Ultramar to the west of the Damocles Gulf.