Cocytus I

Cocytus I is the outermost of the twin worlds Cocytus I and Cocytus II, astral bodies at the edge of the Sentinel Sector and the Eye of Terror. They lie in Segmentum Obscurus. No finer placement is attested, and these are the Forgotten Wars worlds of that name.

The system is remembered chiefly for the Forgotten Wars, a conflict that began when Librarians traced a quarry to Cocytus I. The Lions Sable strike cruiser Fury of Caliban carried companies of the Dark Angels, the Angels of Vengeance, the Angels of Redemption and the Lions Sable through the warp storms that mark this edge of the Eye of Terror, and a strike force made planetfall there. When a signal attributed to Cypher was reported on the planet, Supreme Grand Master Purson ordered the attack pressed and despatched a second ship in support.

The fighting drew in half of the Dark Angels and the Angels of Redemption, three companies of the Angels of Vengeance, and the entire Lions Sable Chapter, as the Unforgiven razed the dens of cultists, mutants and renegades across the wasteland continents of both Cocytus I and Cocytus II. Cypher himself eluded the Unforgiven twice, sending messages that urged them to withdraw and warned that the hunt was a trap. As the warp storms began to close, Purson ordered a retreat; the Lions Sable refused to break off, and Purson returned to the surface with only his bodyguard, leaving orders for the six ships then in orbit to clear the Eye.

That was the last that was seen of Purson or the Lions Sable Chapter. The frigate Vendetta was lost into the warp as the fleet withdrew, and the remaining ships escaped past the Cadian Gate while only a few years passed within the storms, against more than a thousand years in realspace. When a later task force reached the system, no trace of Cocytus I or its twin could be found, leaving the planet’s final fate as unrecorded as the date of its disappearance.