Timeline of the Warhammer 40,000 Universe - 13th Black Crusade (995.999.M41): The 13th Black Crusade is the most recent and the greatest of the incursions launched against the Imperium by the Chaos Lord Abaddon the Despoiler, and was the greatest conflict fought between the forces of Chaos and the Imperium of Man since the Horus Heresy. Under the command of the Warmaster of Chaos, the Traitor Legions poured out from the Eye of Terror, emptying a hundred Daemon Worlds and bursting into realspace in hitherto unforeseen numbers.The armies of Chaos started at the Cadian Gate in a great push towards Terra. The goal of the Chaos forces was the Fortress World of Cadia, the capture of which was the ultimate goal of the forces of Chaos since it would allow them to create a forward base for a new drive upon Terra to topple the Emperor from the Golden Throne and end their Long War.Rumours persisted that the Daemon Primarchs rode at the head of the armies of the Traitor Legions, returned to the mortal realm to usher in the End Times. Imperial forces counterattacked, but there was no end to the forces of the Dark Gods. Despite the best efforts of the Imperium's staunchest defenders -- including the Black Templars, Imperial Fists, Dark Angels and Space Wolves -- Cadia, lynchpin of the defences surrounding the Cadian Gate, eventually fell to Chaos after Abaddon himself arrived with an even larger force of the Black Fleet following Cadia's successful defence of the first Chaos incursion.After a further heroic Imperial effort led by the Lord Castellan Ursarkar E. Creed and the Living Saint Celestine delayed the Warmaster of Chaos' plans to personally seize the prize he had long coveted, Abaddon deployed one of the Blackstone Fortresses he had acquired in the Gothic War, the Will of Eternity. Destroyed by the Imperial Fists' mobile star fortress Phalanx before its Warp Cannon could be used to eliminate all life on Cadia, the Despoiler turned even the fortress' floating corpse into a weapon.Its massive remains were flung from orbit onto the surface of Cadia as an artificial meteor, its kinetic impact killing most of Cadia's remaining defenders and at last allowing the Eye of Terror to swallow the world. The geothermal stress caused by the fortress' impact ultimately caused Cadia to rip itself apart. With Cadia and its Warp-repulsing blackstone pylons destroyed, the Eye of Terror began to expand across the galaxy in what the Chaos forces called the "Crimson Path" even as Abaddon at last realised his dream of seizing the Cadian Gate for the forces of Chaos.With the first goal of the 13th Black Crusade achieved, Abaddon next turned to launching an assault upon Terra itself. However, the inherent fractious nature of the forces of Chaos, combined with the unexpected continued resistance of Imperial forces remaining in the Cadian Gate region, slowed the Chaos advance as the Heretics began to consolidate their gains. A new Chaos empire soon grew up around the shattered remains of Cadia itself.Finally, even as multiple calamities loomed over the Imperium, on Terra the Adeptus Mechanicus secretly reported to the High Lords of Terra in 986.999.M41 that the mechanisms of the Golden Throne were failing and they no longer possessed the knowledge required to repair that ancient piece of technology. Unless something could be done, the God-Emperor would die and then Humanity would face the drawing darkness alone...