Dark Angels - After the Horus Heresy: With their primarch missing and their battle-brothers on Caliban having betrayed them to Chaos, the Dark Angels swore to redeem themselves in the eyes of the Emperor and force the Fallen Angels to repent or die. They decided the true story of treachery behind the destruction of Caliban must remain secret; no outsider must learn of the schism that had split the Ist Legion, or that any Dark Angels had ever turned to the service of the Ruinous Powers.Should the truth be revealed, the Dark Angels believed that they would be labelled Excommunicate Traitoris and never given a chance to redeem themselves. The senior members of the Legion formed a secret conclave -- an Inner Circle of the Legion's Masters.They created an overlapping system to watch over their own Brothers, and also themselves. Everyone must be scrutinised for signs of corruption. Thus started a spiral of mistrust and secrecy that continues to this day.Such was the scale of the disaster of the Fall of Caliban that there could be no hiding it. Psykers across the galaxy had sensed the Warp Storm that ripped the world apart, and the titanic flash of the tempest meeting the indomitable force field surrounding the Dark Angels' fortress-monastery had blazed like a supernova.However, the Dark Angels erected a systematic cover-up of the truth, for each remaining battle-brother of the Ist Legion had taken stringent vows of unspeakable binding to never reveal what really took place on Caliban.Their story might not have held up under an intense inquiry, but it was a time of great upheaval in the Imperium and the retreating Traitor Legions were bolder near the Eye of Terror: the Night Lords, in particular, laid many ambushes that took a high toll on their Imperial pursuers. That a Warp Storm had claimed the Dark Angels' homeworld, and so many of their brethren, was but another tragedy in a deluge of grim tidings.Inquiries found the Dark Angels battered, grief-stricken and bereft of reinforcements, but there was little time for any succour, for war called. Across the galaxy, Traitor strongholds remained and many rebellious planets had yet to be shown the error of their judgement, but most ominous of all was the rise of the xenos threat.Much of the Imperium's strength had been siphoned off in the civil war and so countless planets found themselves at the mercy of a new wave of xenos attacks. Leaving only those necessary to oversee the work being done on the reconstruction of what would become The Rock, the Dark Angels split their remaining Legion fleet in an attempt to answer the many distress calls that reached them.In the Cadian Sector they joined the Blood Angels, themselves still reeling from the loss of their Primarch Sanguinius during the Siege of Terra. Together, like vengeful angels, they drove the Traitors and daemons alike into exile.On Seption Prime, Dark Angels Terminator companies arrived just in time to provide a rearguard action, allowing the Ultramarines to extract their forces before that Plague Planet lost to the pestilential whims of Nurgle was destroyed by Exterminatus.All who fought alongside the Dark Angels at this time lauded them as steadfast warriors, utterly dedicated to the destruction of the Emperor's enemies.Upon their return to The Rock, the much-depleted Dark Angels found disturbing news. At the time of the Fall of Caliban, the Dark Angels thought their traitorous brethren had all been destroyed, vanquished in the Warp Storm that blossomed in the death throes of their homeworld. The Fallen Angels had been swept into the vortex of that horrific rent in the galaxy, but the fury of the Dark Gods had not slain them.The scryings of the Legion's Librarians searched long and hard for their missing primarch and of him they could read no signs. They did, however, pick up traces of the Fallen and determined that the Traitors yet lived, although what remained of their psychic signatures were widespread, and the connections were already fading out of mindsight.