Massacre at Darkmor
The Massacre at Darkmor began, when the scrying of Librarians from six Unforgiven Chapters, determined that the Great Rift would cause a group of Fallen Angels to materialize on the Shrine World Darkmor. Luckily, the Warp Storms surrounding Darkmor had subsided by then, so elements from all six Chapters were all able to arrive on the Shrine World to intercept the Fallen. However, the Unforgiven soon discovered that Darkmor's population had been slaughtered by Daemons and Chaos Space Marines, who had been lying in wait for them. As the hordes of Chaos attacked the Unforgiven, Darkmor was once again struck by Warp Storms that prevented their escape and in the ensuing massacre the Dark Angels' Successor Chapters, suffer losses not seen since the Forgotten Wars. Among those who suffered the most grievous losses were the Angels of Vengeance, Consecrators and Guardians of the Covenant Chapters, who had each sent multiple Companies into the Fallen's well-orchestrated trap. Of the thousand-strong Unforgiven force that arrived on Darkmor, less than a hundred were able to escape the massacre, though only because they pursued the fleeing Fallen Angel Cypher, who led them to a secret teleportation device.