Event · M31

Luther’s Betrayal / Fall of Caliban

Luther’s Betrayal, or the Fall of Caliban, was the civil war in which Luther’s garrison turned Caliban against Lion El’Jonson, destroying the planet. The conflict took place in the early 31st millennium, as the primarch returned to his home system after the Horus Heresy on Terra. Only the asteroid fortress-monastery known as the Rock survived the destruction of the world. Caliban was a forested death world (a planet hostile to human habitation) and the home world of the Dark Angels Space Marine Legion. Its knightly orders hunted the world’s great beasts long before the Emperor’s Great Crusade reached the system, and it was among these orders that the young Lion El’Jonson was found and raised. Luther, his mentor and closest companion, was later left in command of the Legion’s garrison on Caliban while the primarch led the Dark Angels across the galaxy. Isolation, resentment, and the influence of the Ruinous Powers turned Luther and much of the garrison against their absent primarch. When Lion El’Jonson returned to Caliban after the Heresy, Luther’s faction attacked his fleet, and the ensuing battle broke the planet apart. The Rock endured both the bombardment and the warp storm (a disturbance in the extradimensional realm through which interstellar travel and communication are conducted) that followed the world’s ruin. The primarch himself disappeared amid the destruction and was not seen again for ten thousand years. Those of Luther’s followers who escaped became known among the Dark Angels as the Fallen, and hunting them down became an unspoken duty of the Legion’s successor chapters. Cypher and Azrael are recorded as continuing this unfinished pursuit from the remnant of the Rock, across the Camarth and Somnium theatres. The event is also known as the Fall of Caliban. The Order’s office of Lord Cypher, keeper of its laws and traditions, figured in the rebellion: a Lord Cypher was among Luther’s advisers in its first stages, and Zahariel El’Zurias was raised to the title by Luther after his predecessor tried to kill him in a coup. The Cypher active in the 41st millennium is said to be one of the Fallen scattered by the warp storm, though whether he is either of these office-holders is not established.

See where Luther’s Betrayal / Fall of Caliban occurred on the galactic map during the Horus Heresy.

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