Luther - Betrayal: Though supposedly accorded a great honour, Luther felt they had been exiled by the man he had raised as a son. The departure of Luther and the rest had been sudden, almost businesslike, and at the time it had been assumed that they would be back with the fleet before long. But five solar decades had passed, and Jonson had never spoken of them again -- he no longer even read the regular dispatches from Caliban, relegating that task to members of his staff.Luther and the rest seemed to have been entirely banished from the primarch's mind, and as the years lengthened into solar decades, rumour and speculation had begun to circulate through the ranks of the Dark Angels still on the crusade. Some suggested a falling out between Jonson and Luther over the near-disaster at Sarosh, of old jealousies and petty enmities rising to the fore.Others speculated that Luther and the rest bore the blame for allowing the Saroshi bomb aboard the Invincible Reason, which led to sometimes-heated debates between the Terran and Calibanite factions within the Legion. Primarch Jonson made no attempt to address any of the rumours, and over time they were forgotten.No one spoke of the exiles much any more, except as a cautionary tale to new initiates: once you fell from grace with Lion El'Jonson, you were never likely to rise again.Fifty Terran years later, following the great success in the recruitment, training, and equipping of new Astartes for the Dark Angels, Luther and his lieutenants were faced by a widespread rebellion on Caliban. Following Librarian Zahariel's investigations, it was revealed that Caliban was plagued by a resurgence of the great beasts that once ran amok across their homeworld.This dire threat was further compounded by the insurgency raised against them which included former knights of The Order who felt that the Lion had betrayed them. At the centre of this conspiracy was a mysterious cabal of Terran sorcerers that were somehow linked to the reemergence of the Warp-spawned beasts and hordes of undead corpses.Learning of the Warmaster Horus' rebellion against the Emperor, Luther decided that in the best interests of Caliban, he was compelled to declare their world's independence in opposition to both Terra and their primarch alike.The Dark Angels had been posted to the Eastern Fringe of the galaxy when word reached them of Horus's treachery against the Imperium. It is known that the Warmaster ordered the Night Lords Traitor Legion to intercept the Dark Angels and prevent them from aiding the Emperor on Terra, but without success.As the Dark Angels were in transit to Terra alongside the Space Wolves Legion, so too was the Ultramarines Legion, who had also thwarted Horus' best efforts to keep them from Terra after the Battle of Calth. The three Legions arrived too late; Horus had been defeated and the Emperor grievously wounded, his shattered body placed within the life-support mechanisms of the arcane Golden Throne.Grief-stricken, Jonson returned to Caliban. Upon the Dark Angels' arrival in orbit, they were fired upon from the surface. Pulling back the fleet, El'Jonson tried to find out what had happened, and discovered that Luther -- who had become embittered by what he perceived as El'Jonson always taking all the glory -- had poisoned the minds of the Dark Angels garrison and the new recruits that had been left on the planet against their primarch. Correctly believing that Luther and the planet-side Dark Angels had actually been tainted by Chaos like the Astartes of the Traitor Legions, an infuriated Jonson ordered that Caliban be bombarded from orbit, destroying the planet's defences.El'Jonson then led his forces to the surface and assaulted The Order's fortress-monastery, where he confronted Luther in single combat. Luther, transformed into a Chaos Champion by the power of the Chaos Gods, was now finally evenly matched in strength with the enraged primarch. The battle between the two levelled The Order's fortress-monastery as the planet was coming apart around them, the orbital bombardment taking a heavy toll on the surface.El'Jonson managed to wound Luther, but could not bring himself to kill the man who had been his brother and mentor. Luther lashed out with a powerful sorcerous attack that mortally wounded the primarch. As he saw what he had done, Luther felt a veil lift from his eyes, and the Chaos Gods -- seeing that once again their chosen Champion had failed to defeat the lackeys of the Emperor -- lashed out with the powers of the Warp.The Fallen Angels were scattered throughout space and time as the Warp swallowed them, and Caliban tore itself apart under the strain of the Ruinous Powers' assault. The only portion of the planet remaining intact was the rock on which stood the fortress-monastery in which Luther and the Lion had dueled.The Dark Angels entered the shattered monastery and captured the broken Luther; of El'Jonson himself, however, there was no sign. It was believed that Jonson was thrown into space and time along with the Fallen, but the truth was that the Lion still lived, though he had been placed into a coma.