After the events of the Horus Heresy, the Dark Angels returned back "home" to Caliban. Only, whilst they had been away, the powers of Chaos had whispered sweet nothings in to Luther's ears and caused him to fall under their sway. His followers ultimately went on to become the "Fallen" whilst the Dark Angels - and even their successor chapters - started to refer to themselves as the "Unforgiven" over this event.
During this encounter, the Dark Angels ultimately decide to bomb Caliban in to space debris. The largest chunk of it, The Rock, became their home with The Lion ultimately occupying its deepest recesses in deep sleep.
What has bothered me about this sequence of events recently is how the Dark Angels ultimately justified the destruction of their home world. Imagine this: you are a scribe (of a very senior rank) in the administration. The Dark Angels suddenly say they've bombed their home planet in the smithereens. You report this. You're asked to query this. Why did they do this? What justification was there to use such excessive force? They say, they dunno. Because we keep our secrets.
How does the blowing up of a planet escape notice because "secrets"? Especially given how Istvaan III's death screams were heard from such a vast distance away by the Astronomicon.
So, my question today, is what was the reason, or the cover story, given by the Dark Angels to destroy Caliban -- given that they want to keep quiet about Luther and the Fallen?
Perhaps its just because Grimdark. The processing of the order to investigate the "why" and "wherefore" never got processed. Perhaps is just is "secrets". But didn't anyone notice that Caliban was now a Rock? How do they continually keep this a secret?
(Disclaimer: my long term readers will know I have a soft spot for the Dark Angels, so please don't shoot!).