The siege of terra

[Grand Master Tyrak]

Also, Caliban was brought into compliance, so it wasn't behind enemy lines or anything. Just close to the Eye of Terror which, with the pre-Heresy attitudes we see towards Chaos, would have been seen as a space phenomena and nothing else.

 

During the Heresy, any outlying systems far from Terra would have been easy meat for renegades, traitors and xenos, since all the Legions went rushing back to Terra. Plus, the defeated Traitors came back that way when they fled into the Eye. This isn't pre-Heresy I'm referring to. If it was, you would be right.

[Hobo Willie]

But that's the thing, Luther and his Astartes had been sitting on Caliban for quite a while, so it would have to be pre-heresy as well.

[Jamafore]

I had heard it as the Dark Angels had stopped at Caliban to resupply and reinforce on their way to Terra, when they found out about the Fallen. So that would suggest it happened during the heresy and the Angels headed to the seige after they blew their planet to hell.

 

Maybe I read it wrong.

[Grey Mage]

What I've never understood about the Dark Angel's fluff is why half the entire Legion was left on Caliban. According to everything I've read, the Great Crusade was getting stretched thin, at least in terms of Astartes to Expeditions. Why would Horus or the Emperor allow half of a Legion to sit on one planet? This would be somewhere around 5000+ Astartes. And it could be as much as ten times that depending on the size of the Legions.

 

I suspect it was half the Dark Angels at the point the Loyalists returned to Caliban. So, whilst it may have been around a thousand Marines or more (particularly since Caliban is far away form Terra, and deep in what would have been enemy territory), when they were left there they wouldn't have been half the Legion. By the time the Loyalist DA returned, their numbers would have been thinned by the Heresy and so they would have no numerical advantage over Luther's men.

 

Actually they talk about how luther and a majority of the "full" marines who were on caliban were in fact not full marines. They were augmented humans but had been to old when the emperor showed up to make the full transition. The rest of the marines there were initiates... they were being trained. The full marines were out fighting, the "old gaurd" were training the raw recuits... and thats what the legion came back to- iniates warped by the teachings of elders who were driven to chaos out of jealousy and self esteem issues.