Abaddon the Despoiler launched his 5th Black Crusade out of the Eye of Terror in 723.M36, one of his infamous incursions into the realms of the Imperium of Mankind. The campaign is also remembered as the "Tide of Blood," "the Scouring of Elysia," and the "Black Crusade of Doombreed." Abaddon's forces scoured the Elysia Sector, raiding hundreds of worlds and causing untold death and destruction.
On the world of Tarinth, the Despoiler lured the Warhawks and Venerators Chapters of Space Marines into the ruins of the ancient Imperial city of Kasyr Lutein where he trapped them between the daemonic hordes of Khorne and the Heretic Astartes forces of the Black Legion.
In a bitter last stand, both Loyalist Chapters were utterly destroyed, their skulls taken by the ancient Daemon Prince Doombreed, whose existence precedes that of the Imperium itself, to be mounted upon the mighty throne of Khorne.
The 5th Black Crusade included among its many atrocities the scouring of the Elysia Sector of the Segmentum Obscurus, culminating in the destruction of the ancient Imperial city of Kasr Lutien on the world of Tarinth. Abaddon purposefully fomented Chaos invasions on a dozen worlds within the sector, entrusting the destruction of Imperial cities, shrines and temples to his warlords while using his Black Fleet to keep the Imperial Navy's Battlefleet Obscurus engaged in deep void skirmishes. It was Abaddon's intention to create a sector-wide conflict that would provoke a massive response from the Imperium and draw in Chapters of the Adeptus Astartes. His plans set in motion, Abaddon led the bulk of his Black Legion to the city of Kasr Lutien on the world of Tarinth, burning the great city to the ground and enslaving its people.
When the Warhawks and Venerators Space Marines arrived on Tarinth in Chapter-size strength, they made an immediate assault upon Kasyr Lutien. At the same moment, Abaddon ordered the mass sacrifice of ten million Imperial citizens. Their blood funnelled via the city's great canals into a vast lake of gore. Above the lake, a rift into the Warp cracked open and the Daemon Prince Doombreed stepped into reality, howling in triumph.
Abaddon had made a dark pact with Doombreed, promising it the skulls of an entire Chapter of Space Marines in return for its service. With thousands of Bloodletters pouring forth from the lake of blood, Doombreed waded into the ranks of the Warhawks and Venerators. The Black Legion then sprang their own trap, and from prepared positions across the city, they opened fire on the Loyalists, blocking their retreat. Though they fought without fear or respite, both Chapters fell that day, their warriors mutilated by the daemonic host and their gene-seed forever lost to the Imperium. The skulls of the fallen Space Marines were taken by Doombreed to be mounted upon the mighty throne of the Blood God.
Among the forces mobilised against Doombreed was a contingent of Blood Angels aboard the Battle Barge Eclipse of Hope. The Battle Barge disappeared during the Crusade when the Blood Angels aboard sacrificed their own freedom to imprison Doombreed on the planet Pallevon.
While the Imperial forces battled against Abaddon's assault, a Flawless Host warband led by squads of Possessed Chaos Space Marines tormented the Agri-worlds of Galvan II and Galvan IV. Not only did they smash their way through Imperial defence emplacements which were woefully undermanned as Abaddon's forces kept reinforcements from reaching the beleaguered worlds -- but they went on to horrifically massacre the populations of several cities. The Possessed raided Imperial temples and sacred shrines, seizing powerful artefacts of the Imperial Creed that Abaddon had requested of them. Not satisfied with all that they had taken, Flawless Host destroyed both worlds' orbital shipyards and major manufactoria before leaving orbit with their prizes, delivering a critical blow to the Imperium during a dark hour.
In truth, while the Chaos victories were savoured in their own right by the Warmaster of Chaos and his dark servants, their purpose had also been to loosen the psychic equilibrium in the Elysia Sector. Each act of violation and violent horror shattered the divide between the Warp and realspace that prevented an increase in psychic mutation in that part of the galaxy. In truth, the 5th Black Crusade, like all the Black Crusades before the 13th, was intended to further weaken the barriers between the mortal realm and the Warp, in the hopes of eventually giving birth to the Great Rift and the final destruction of the Emperor's domain.
- Black Legon: A Codex Chaos Space Marine Supplement (Digital Edition), pg. 34
- Codex Heretic Astartes - Chaos Space Marines (8th Edition), pg. 23
- Codex: Chaos (2nd Edition), pp. 139-140
- Eclipse of Hope (Short Story) by David Annandale
- Index Chaotica: Possessed
- Liber Chaotica: Khorne, pg. 84
- Mephiston: Lord of Death (Novella) by David Annandale, Ch. 9