The Dark Angels returned to Caliban after the war and found their brethren had betrayed them. They were forced to assault their own homeworld.
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The Dark Angels returned to Caliban after the war, but they were fired upon by the planetary defenses. They were forced to assault their own homeworld, where they found that their brethren had betrayed them. In a duel which mirrored that of the Emperor and Horus, Luther and Lion El’Jonson fought, resulting in Luther mortally wounding his former friend. Luther went insane upon realizing he had struck down his close friend and was captured. In a fit of rage at being defeated once again, the Chaos Gods opened a warp rift in the planet which scattered the traitorous “Fallen Angels” throughout the galaxy.
Other sources state that the Warp Rift was caused by a causal loop in the 41st Millennium after Azrael, Cypher, Typhus, and others attempted to rewrite the history of Caliban with the Tuchulcha Engine. Regardless of the truth, one of the “Fallen Angels” who escaped is Cypher, who reportedly took with him the Lion Blade, the sword of El’Jonson, when he was sent through the warp.
The Dark Angel space fleet also bombarded the planet mercilessly, and this caused the structure of the planet to collapse. The bombardment, combined with the newly formed warp rift, broke the planet up and it is now an asteroid field. This betrayal has tainted their honor in the eyes of the Dark Angels themselves. Given that the event was purely within the Legion itself, and was on a world far from Terra, nobody outside of the Legion knows it occurred. Within the Chapters itself, only the elite veterans are permitted this knowledge – in the modern Dark Angels Chapter, only the Deathwing and senior officers know this secret.
The Chapter leadership will go to great lengths to ensure that this knowledge does not reach the Imperium at large, even at times going so far as to disobey direct orders from Inquisitors and cause overly curious individuals to “disappear”. Only the most senior members, known as the Inner Circle, know the greatest secret – that Luther, the great traitor, is still alive and insane, living in a cell deep within the Rock. Lion El’Jonson’s body was supposedly never found; Luther claims, in his near-senseless mutterings, that the Lion is near and will return and forgive him. The Lion actually sleeps in the most secret chamber in the rock, his presence known only by the Watchers in the Dark and the Emperor himself, until the time he will awaken and lead his chapter on a new and even greater crusade.
That day, so Luther said to current Supreme Grand Master Azrael, is almost at hand.
Caliban was destroyed during the Betrayal, shattered by the warp rift and orbital bombardment. The remains now form a sizeable asteroid field. The largest piece, which survived due to the massive void shields in operation around the largest fortress-monastery, called the Tower of Angels, was hollowed out and became a gigantic spaceship/monastery which is now the home of the Dark Angels. This ship is known simply as The Rock.
Sometime after the Betrayal, the Dark Angels changed their primary heraldry colour from black to dark green. Lion El’Jonson had previously decreed that Dark Angels could change their armor to green in memory of the war against the Great Beasts of Caliban. This story of treachery and betrayal is the Dark Angels’ secret shame. None know of it other than some of the Dark Angels, their Successor Chapters and, maybe, the Emperor on his Golden Throne. Within the Chapter itself very few Brother-Marines know exactly what happened during those fateful days.
Read More About The Dark Angels During the Betrayal
