Well the only thing Dark Crusade does is tell they won the war on Kronus but in doing so the Inquisition started to probe into them and became interested in their past because of their willingness to kill Guardsmen. To be honest the Blood Ravens got a bum rap because their Chapter Master sent them to purge the planet and Segmentum sent Lucas Alexander to Liberate the world. Technically the Space Marine orders supersede that of the Imperial Guard as they are higher ranking in the Imperial war machine. However, this is the Imperium of Man and nothing is ever that simple. Because Segmentum sanctioned the Imperial Guard mission and not the Blood Raven's and because Segmentum Command is tied to that of the Imperial government Thule should have backed down and left or assisted. But he didn't.
The books are not Dark Crusade and Dark Crusade are not the books. From what Ulysses is telling me the books are part of the Dawn of War universe as well.
Here's where I'm confused. Since the books and games do not create a cohesive canon. Which one supersedes the other?