User blog comment:Vivaporius/AT Idea: Imperial Civil War/@comment-3341288-20120407013402/@comment-3398633-20120407181855

Well the basic idea is this:

The Emperor has been declared an imposter. The marines are thus divided into those who thinks he's the real deal, and those who believe his a man how has commited the greatest level of heresy possible. Since the Emperor can't very well go out and clear his name in his fragile state, the Astartes are thus left to their own devices. I'm thinking of a meeting where the Emperor summons the most loyal masters of the chapters, and combines them into pseudo-Legions, that work together in a more intimate manner. Thus, you have your Imperial chapters, and your Theocratic chapters, each attempting to warn their brothers that they are being mislead.