Cadia - 13th Black Crusade and Fall of Cadia: In 999.M41, when Abaddon the Despoiler finally launched his 13th Black Crusade, the greatest Chaos assault on the Imperium since the Horus Heresy, the forces of Chaos managed to make landfall upon Cadia itself and occupy large swathes of the planet despite ferocious Imperial resistance.The campaign was kicked off by the unexpected betrayal of the Volscani Cataphracts of the Astra Militarum, whose regiments successfully assassinated the Cadian High Command, including the Lord Castellan, the Cadian planetary governor and leader of its armed forces.Led by the skilled strategist Ursarkar E. Creed, the colonel of the 8th Cadian Regiment who was suddenly vaulted to the position of Lord Castellan, the Imperial forces were able to contain the initial Chaos assault and hunt down most of the occupying forces after the defeat of the initial Chaos armada in orbit.Unfortunately, the Despoiler had barely begun to fight. He unleashed a massive second Chaos warfleet on the Cadian System and a ground assault that was led by one of his Chosen, Urkanthos, the Lord Purgator of the Black Legion.Urkanthos led a massive horde of Chaos Space Marines, Chaos Cultists and Daemons against Kasr Kraf, the Cadian fortress-city that represented the primary centre of Imperial resistance. When Urkanthos was slain in the wake of the Living Saint Celestine's arrival and Kasr Kraf was saved, she bought the Imperials enough time to move their defence to the Elysion Fields, the largest grouping of Cadian Pylons on the planet. It had become clear in the course of events that Abaddon's true reason for constantly assaulting Cadia through his Black Crusades had always been the destruction of these pylons.The Archmagos Dominus Belisarius Cawl, another recent arrival to the Fortress World, had been led to Cadia by the Harlequin Shadowseer Sylandri Veilwalker, and believed that he could decipher the true function of the pylons.With the aid of the Necron Lord Trazyn the Infinite, who had been present when the pylons were first constructed, Cawl proved capable of mastering the enigmatic xenos artefacts' internal systems deep in the catacombs beneath the pylon field. But this came just in time for Abaddon to launch his final ground assault against the Elysion Fields, as the Despoiler was determined to assuage his pride by personally ending the Imperial defence.Once Cawl successfully activated the pylon network and cut off the access of the assaulting Chaos forces to the Warp -- even the Eye of Terror began to shrink as it was struck by the pylons' anti-psychic emissions -- Abaddon abandoned his desire to crush Cadia's defenders personally.Finding a modicum of grudging respect within himself for the Imperials' valour, the Despoiler decided instead to unleash his horrific fail-safe plan. He launched the remaining bulk of the Blackstone Fortress Will of Eternity, badly damaged by the assault of the Imperial Fists' star fortress Phalanx, into the surface of Cadia like an artificial meteor.Cadia shuddered from that impact, as impossible forces jarred it loose of its age-old orbit. The survivors clinging to the ruined fortresses of the continent of Cadia Tertius barely had time to scream. Those beneath the vast impact site perished first, super-heated wind roaring in their ears before it seared flesh from bone, and reduced bone to scattered ash.The Blackstone Fortress' remnant struck, gouging a crater hundreds of miles in breadth. Mountains crumbled to dust. Seas vanished into plumes of scalding steam. Continental plates rumbled and groaned as they shifted beneath titanic forces not seen since Cadia first cooled from the star-stuff of the galactic void.The tremors spread, tidal waves and screaming particulate winds their heralds. Coastal bastions that had survived bombardment and siege drowned beneath the unnatural tide, ripped from their foundations and dragged beneath the squalling seas. The island of Ran Storn vanished entirely, its shell-ravaged landing fields drowned beneath the waves. A thousand miles inland on the continent of Cadia Secundus, the enduring spires of Kasr Vark at last fell, smashed apart by the waters of the Caducades Sea as the tidal shelves buckled.Forests that had been old when Humanity first settled Cadia burned away in the briefest of moments. Crustal platelets shattered and split, the furious life-blood of the world boiling forth. Long-dormant volcanoes flared to life along the Rossvar Mountains, pyroclastic flows consuming all in their path. The great killing fields of Tyrok, site of Creed's ascension to the rank of Lord Castellan, split asunder and vanished into magma-lit gloom, swallowed by the world's torment.At the Elysion Fields, half a world away from the impact site, they heard the roar of the winds, and saw the dark onrush of particulate clouds that blocked out the sun. The canny sought what cover they could amongst the pylons and ruined war machines. The slow-witted perished, torn apart by the vaporised bones of Cadia.The winds grew, hurling tanks across the pylon fields, crushing those who had sought shelter beneath them. The ancient pylons gave up their grasp on the bedrock, toppling like petrified trees. The pylon field's beam of dark light cast outwards into the void flickered as the monoliths fell. The retreat of the Immaterium faltered, and then slowly reversed as the Eye of Terror began to expand once more.The storm raged for solar minutes that seemed eternities, and then fell away into hurricane winds. They blew over a world forever altered. The continent of Cadia Tertius was gone, obliterated by fire and drowned beneath howling seas. The Krian Fault, bane of the continent of Cadia Tertius since the Age of Strife, had ruptured one last, fateful time, and the planetary crust split apart.The continent of Cadia Primus was half-drowned, its forested mountainsides now isolated islands scattered across a new ocean. Cadia Secundus lay wreathed in fire, its continental plates sinking as the pressure of their neighbours forced them steadily inwards. None of it mattered. Cadia was already dead.But even then, there was worse to come. As the aftershocks of impact rippled through the dying rock, more pylons shattered against the dust-strewn tundra -- not just at the Elysion Fields, but at the lesser sites of Kasarn, Trosk and Vorg. As the pylons fell, the nodal web stuttered, and then withered entirely. The dark light beam, Belisarius Cawl's dagger struck into the heart of the Eye of Terror, flickered once more, and died. A new sound pealed through the howling winds -- the dark laughter of gods too long denied their prize. The crimson maelstrom of the Eye of Terror pulsed anew, and reached out to embrace sundered Cadia.Save for the presence of the pylons, the Immaterium would have claimed Cadia long ago. The long-dead Necron artisans who had set the pylon fields in Cadia's living rock could not have foreseen the Eye of Terror's cataclysmic birth, could not have known the vital bulwark their works would become. But now, with the pylons' fall, the tendrils of the Warp laid their first loving caress upon Cadian realspace, and the daemons of the Dark Gods spilled forth.These were not the flickering manifestations so lately loosed upon the world, their presence in realspace under constant challenge by the pylons' power. These were the servants of the Ruinous Powers, hale and whole, fed by the raw stuff of Chaos. They first appeared amidst drowned Cadia Tertius, where the Blackstone Fortress' demise had torn a rent in reality's veil through the sheer loss of life. But as the Eye of Terror slipped its ancient bounds, the rifts multiplied, dragging the beleaguered world into the bowels of the Immaterium.The monstrous kinetic strike wiped out most of Cadia's remaining defenders, destroyed the network of Cadian Pylons and tectonically destabilised the world. As the Warp and its foul denizens claimed the remains of the Fortress World, Lord Castellan Ursarkar E. Creed arranged an evacuation of the planet that saved 3 million of its citizens before the planet finally ripped itself apart -- though not before Creed himself mysteriously disappeared.The fall of Cadia represented a once-unimaginable triumph for the servants of the Dark Gods, and the Eye of Terror began to slowly expand without limit, opening Abaddon the Despoiler's coveted Crimson Path to Terra and creating the Great Rift that soon divided the Imperium in half.Yet among the few survivors of Cadia was a handful of Imperial heroes who had successfully escaped the destruction of the Fortress World with the aid of the newborn Aeldari faction known as the Ynnari. The combined forces fled through a Webway gate found on the ice moon of Klaisus in the Cadian System.Together, these Imperials -- the so-called Celestinian Crusade -- would forge an uneasy alliance with the enigmatic xenos that would offer a new hope for the servants of the Emperor in their fight against the waxing power of the Archenemy -- the resurrection of the Primarch Roboute Guilliman.