The Deathmongers are a warband of Chaos Space Marines. They were once a Loyalist Chapter of Space Marines of unknown origin and Founding, known as the Brothers of the Anvil. They were corrupted after entering the Eye of Terror in 321.M37 as part of the Imperial Abyssal Crusade.
During their sojourn into the Eye, they landed upon the ancient Eldar Crone World of Belial IV and were captured by xenos Kabalites. After enduring horrific torture at the hands of their Drukhari captors the remains of the Brothers of the Anvil slaughtered their way back into realspace, unrecognisable as a formerly loyal Chapter.
As the Deathmongers, they have a brutal reputation for causing wanton destruction during their campaigns, even to the point that they will cede a possible victory for the opportunity to cause more death and devastation for its own sake.
The Deathmongers were a formerly Loyalist Chapter known as the Brothers of the Anvil. Following the Ecclesiarchal Purges of 321.M37, a dozen star systems were engulfed by Warp Storm Dionys, its echoes rippling along the spiral arms of the galaxy as it raged through the Empyrean. Records of mutation and Chaos Cultist activity quadrupled overnight.
Worse yet, it was not only the citizens who were affected by the sudden influx of Chaos. Many of the Space Marine Chapters with homeworlds affected by the Warp Storm found that the secret imperfections in their gene-seed were writ large upon their new recruits, giving rise to a wave of disturbing manifestations both physical and psychological. The Brothers of the Anvil were one such Loyalist Chapter of Astartes that had been affected by these Warp Storms.
When the Ecclesiarchy heard of this sinister turn of events, Saint Basillius the Elder demanded that all those Chapters of the Adeptus Astartes whose homeworlds had been touched by the Warp Storm be rendered unto his judgement. Such was the elder's influence with the High Lords of Terra that within a standard year this had come to pass. After a series of stringent tests and prognostications, hundreds of Chapters were deemed unaffected by the Warp Storm.
No less than thirty were found wanting. The Judged, as these fallen Chapters came to be known, volunteered for a redemptive Penitent Crusade. The most militant of their number demanded the right to purify their tainted flesh in the fires of battle, to make a noble end from tragic misfortune. To the surprise of his closest advisors, Saint Basillius agreed to this proposal. He saw it fitting to send the accused into the Eye of Terror, taking the fight for the Imperium's future to the Daemon Worlds inhabited by the Traitor Marines.
A representative from each of the doomed Chapters held an emergency Council of Dismay to discuss the proposed Crusade. After scant solar hours of debate, they acquiesced to Basillius' demands, for they believed that martyrdom was preferable to an existence of suspicion and doubt. The last few days of 321.M37 saw a solemn procession of Strike Cruisers and Battle Barges pass through the Cadian Gate into the Eye of Terror, relay systems dormant and heraldic colours obscured by black mag-plates.
One by one, the Chapters of The Judged disappeared into the iridescent dust nebulae that surrounded the Eye. As the massive Space Marine flotilla entered the Eye of Terror, they were set upon by a massive Chaos warfleet. The resultant battle was so fierce that the ships of The Judged were forced to retreat and were scattered to the furthest corners of the Eye.
Upon the Crone World of Belial IV, the Brothers of the Anvil scoured the tumbling spires of erected during the time of the original Eldar Empire before the Fall, only to be brought to battle and eventually captured by the Drukhari Kabalites who were also present on the ancient world, searching for arcane artefacts from the Aeldari's lost past.
After a Terran year of nightmarish and torturous ordeals in the Commorrite arenas, the broken remains of the Brothers of the Anvil somehow slaughtered their way back into realspace. But their experiences had changed them, leading them to swear their allegiance to the Dark Gods. Now as the Chaos Space Marine warband called the Deathmongers, they kill every living thing they encounter, and will sometimes forego even victory itself simply for the chance to cause more wanton death and destruction.
Orphean War of Faith
Two millennia later, the Deathmongers found themselves within the Orpheus Sector of the Segmentum Tempestus. In the latter years of the 39th Millennium, much of this sector had been bled by worsening strife and warfare. The majority of the Orphean ruling classes was set against each other in bloody internecine conflict, and the sector itself was balanced on the edge of the abyss. The unhallowed forces of the daemon and Chaos Space Marines drawn from the Deathmongers and the Traitor Alpha Legion and Night Lords were conclusively identified among the rebels.
A ramshackle fleet arrived in the sector capital world of Amarah bringing with it unexpected aid -- an Imperial Crusade force of Imperial zealots, militia, Imperial Guardsmen and pilgrims driven into martial fervour by the preaching of the ecstatic visions of the Arch-Confessor Marduk of Helvamon. Marduk declared a War of Faith for the souls of the Orpheus Sector, claiming the God-Emperor Himself had warned him of a great and terrible threat to all Mankind.
Further reinforcements in the form of the Angels Revenant Space Marine Chapter in its entirety, as well as the Adeptus Sororitas Order of the Valorous Heart and the Order of the Black Sepulchre, and a taskforce from the Ordo Malleus of the Inquisition strengthened the Imperial cause. The Imperial forces were also able to count upon countless volunteers from the citizenry of those worlds as yet untrammelled by war, who have been stirred up by Marduk's religious oratory. Thus began the Orphean War of Faith, a bitter conflict that lasted for nearly twenty standard years and saw a full fifth of the Orpheus Sector's population slain by its end, and countless more ruined, maimed and displaced.
By 921.M39, despite a successful Imperial victory in the Orphean War of Faith, nearly all the major Traitor-held worlds were either reconquered or laid waste save one, the Chaos stronghold of Colkasth. This Hive World had been fortified and corrupted into a living hell, its population used as raw materials by the Warpsmiths of the Deathmongers to fashion flesh-weapons and mutilated and insane cannon-fodder to defend their prize. Despite continuous pressure by the forces of the Arch-Confessor Marduk, the Imperials were unable to reconquer the recalcitrant world.
It is known from the last signals received from the warzone that Marduk's forces were making headway, matching the fury of the Warp-tainted defenders of Colkasth with faith and fire, and had succeeded in forcing multiple landing zones on the planet's surface, when astropathic communications with the besieging Imperial fleet abruptly ceased and the alarm was raised.
The Angels Revenant Strike Cruiser Intercessor was the first to respond to the raised alarm. It was attacked and severely damaged on its arrival at the system's edge by two small but extremely powerful voidcraft of unknown (presumed xenos) origin, now recognised as of Necron manufacture. The Space Marine vessel was damaged before destroying one attacker and driving the other off. Those on the near-crippled Intercessor witnessed a great star battle erupting across the inner system on their long-range Auguries, but are themselves unable to intervene.
By the time they limped to Colkasth, the unknown xenos attacking force had departed, leaving a twisted field of burning hulks drifting in orbit around the world, its fortresses and cities shattered and seething with unearthly radioactive fire below. There were, however, scattered knots of survivors amid the wreckage and fallout.
Those that bore the stigmata of Chaos and treachery the Angels Revenant put to the sword, while those few survivors who fought for the Emperor, wounded and often catatonic with shock, were carried away to salvation before a final ash-black nuclear winter claimed the world.
- Codex Heretic Astartes - Chaos Space Marines (8th Edition) (Revised Codex), pg. 53
- Codex Heretic Astartes - Chaos Space Marines (8th Edition), pg. 53
- Codex: Chaos Space Marines (6th Edition), pg. 19
- Codex: Chaos Space Marines (4th Edition), pg. 70
- Imperial Armour Volume Twelve - The Fall of Orpheus, pp. 21-22