Chaos Space Marine Creation and training

[The Last Lamenter]

I wasn't aware that the rate of betrayal was that high for loyalists, that makes sense about the HH legions not using scouts in the 41st mil. way since csm would most likely adopt the battle doctrine of the original legions. Very good point. You just wouldn't think that the rate of betrayal would be enough to field the number of marines required for a black crusade. What's the current strength thereabouts of the total marines in the imperium, I know what lexicanum says but does any body have another figure?

[Nabterayl]

I don't think anybody has a figure other than "about a million." If they do, I'd love to hear about it.

Black Crusades, as far as I know, include virtually no Chaos marines by percentage. I don't see how they could. Everything I've ever read suggests that finding even a single Chaos space marine in a Chaos army is about as rare as finding a loyalist space marine. The Thirteenth Black Crusade may have been the biggest gathering of Chaos marines in a very long while, and a very large number of space marines may have responded (roughly 20,000, counting companies), but virtually all of the fighting must have been done by ordinary men and women who probably never even saw a space marine on either side.

As long as you accept the hypothesis that the role and military capabilities of a space marine do not fundamentally change depending on which side of the family tree they're on, the betrayal rate can be high or low. I don't think we can posit numbers for that rate, but the 4th edition CSM codex did a good job, I thought, of pointing out that loyalist marines must and do defect on a regular basis (even if not in large numbers).