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Warhammer 40K: The Dark Mechanicum – Masters of the Soulforges

7 Minute Read
Mar 17 2023

Come and learn of the fallen scions of Mars – the Dark Mechanicum who turned their backs on the Omnissiah in a mad lust for power.

The Dark Mechanicum, referred to by themselves as the New Mechanicum, is a Chaos-affiliated sect of the Adeptus Mechanicus. Its origins trace back to those who pledged loyalty to Warmaster Horus at the end of the Great Crusade. The Dark Mechanicum serves as a dark “mirror” to their counterparts within the Imperium.

Early History

Horus gained the loyalty of a sect within the Mechanicum after promising them STC technology gained from the worlds of the Auretian Technocracy and the opening of the vaults of forbidden technology on Mars. In addition, Horus’s emissaries and spies told the Tech-Priests that the Emperor planned to steal the secrets and technology of the Martian Mechanicum and even eventually enslave the Tech-Priests. Lastly, Horus used the ideological schism within the Mechanicum, between those who believed the Emperor was the earthly representation of the Omnissiah and those who still thought such a figure was entombed on Mars, suggesting it was the Emperor himself who had presented himself as their god in a scheme to make him their servants.

Having won over many of the Mechanicum’s Priests, Horus encouraged his new allies to dabble in previously forbidden technologies, gradually enticing them to the powers of Chaos.

Fabricator General Kelbor-Hal, after siding with Horus

In the resulting Schism of Mars, the Dark Mechanicum led by Fabricator-General Kelbor-Hal supported the Warmaster during the start of the Horus Heresy and were present on Istvaan V where they used dark and forbidden knowledge against the Loyalist forces. With the defeat of traitor forces after the Battle of Terra and the subsequent Great Scouring, the Dark Mechanicum fled into the Eye of Terror with their Chaos Space Marine allies.

Current Status

In the 41st Millennium, the Dark Mechanicum are still active, utilizing massive, daemonically corrupted Titan war machines of the Traitor Titan Legions against the Imperium and producing infernal weapons and Daemon Engines from the world of Xana II.


During the Thirteenth Black Crusade, the Dark Mechanicum began invading Imperium worlds that were devastated in the aftermath of the Great Rift‘s creation. Their targets are not picked at random, however, as the Dark Mechanicum are searching for ancient archeotech that will help them complete an unholy weapon of war and terror whose like has not been seen since the Dark Age of Technology.


Unlike their loyal Mechanicum brethren, the Dark Mechanicus has no issue with modifying STC‘s or other forms of sanctioned Imperial technology. As a result they have no qualms in uncovering forbidden technology from the Dark Ages such as the Silica Animus and Anima Mori. Dark Mechanicus technology is heavily intertwined with the Warp and Daemonic and they have no boundaries when it comes to genetic experimentation and advanced cybernetics that push the limit of Humanity. As demonstrated with devices such as the Kaban Machine, the Dark Mechanicum has little to no quams when it comes to the development of Artificial Intelligence.

However of all their esoteric technologies, Daemon Engines are the most infamous technological creations of the Dark Mechanicum. Dark Mechanicum Forge World produce weapons of war for not only themselves but also Chaos Space Marine and other Chaos-affiliated warbands in exchange for slaves and resources.

Dark Mechanicum Forces

The forces of the Dark Mechanicum are an echo to those of their Adeptus Mechanicum brethren. Their Tech-Priests often wear dark red robs while others wear black robes symbolizing their original loyalty to Horus. However there is little standardization, and Dark Magi cabals often decide their own appearance and level of bionics.


Below their Tech-Priest masters, Dark Mechanicus infantry consists of both hordes of expendable drug-fueled Mutant slaves and Servitors alongside crack infantry dubbed Dark Skitarii. These dark mirrors of the Skitarii are heavily mutated and corrupted, often wearing black robes and donning horned helms. Daemons and Possessed are also common infantry in Dark Mechanicum armies. The War Robots of the Dark Mechanicum are steeped in Chaos energy and wield ancient energy weapons. Some Chaos Space Marines have also joined the ranks of the Dark Mechanicum.

Dark Mechanicum armor consist of a wide variety of vehicles. These include anti-grav vehicles and light walkers, Eviscerator Engines, and artillery carriages. They wield a large amount of Daemon Engines, including Defilers and Brass Scorpions. Commonly used aircraft include Hell Blades and Hell Talons.

The Dark Mechanicum still maintains strong ties with the Traitor Titan Legions and Chaos Knights. Dark Tech-Priests maintain ancient Chaos-corrupted Titan and Knight engines in exchange for their services in war. The Warp Entity Vashtorr the Arkifane claims dominion over the warp-technology of the Dark Mechanicus, but any formal relationship, or patronage is unknown.

Key Forge Worlds

Xana II

A Forge World near the Eye of Terror. The history of Xana II began when Tech-Priests of the original Forge Lords of the Xana System declared loyalty to Warmaster Horus during the Horus Heresy. Presumably, they were ultimately forced to flee into the Eye of Terror during the Great Scouring, where they founded Xana II. It’s also possible that the Hereteks of the original Forge of Xana II in Xana’s system somehow moved it to the Eye.

Operated by the Dark Mechanicum, Xana is infamous for its production of advanced wargear and Daemon Engines for the forces of Chaos. The hellish world of Xana II is believed to be a planet wholly given to daemon-machines and infernal industries, where mills grind flesh and countless millions are enslaved to work in its world-spanning factories. The masters of Xana II, often half-daemon machines themselves, have long since given up their humanity and answer to none. They sell their creations to the highest bidder, be they Chaos Space Marines, Daemon Princes, Sorcerers, or warlords and accept only human currency to feed their worlds endless requirements for slaves and souls. Xana II in particular is known for its aircraft, such as the Hell Blade and Hell Talon, which are widely used by the forces of Chaos. The Imperium remains largely ignorant of technology and weapons of the Xana II lineage

The Dark Mechanicus are users of prohibited technology, such as true AI (Abominable Intelligences).



A Forge World near the Maelstrom. During the Age of Strife, the world became an Adeptus Mechanicus station but soon was isolated and embattled. On its own against raiders, xenos, and abhumans and without aid from Mars, the priests of Sarum became isolationists under a cult by their ruler, Redjak. Redjak solidified his Crimson Priesthoods power, taking over much of the Golgothan Sector. However when Sarum faced a massive invasion by the Brotherhood of Ruin and their Ork allies, they plead for aid from the Imperium and finally received it in the form of the World Eaters 13th Expeditionary Fleet, led personally by Angron.

In the ensuing Golgothan Slaughter, the Brotherhood of Ruin was annihilated by the World Eaters. However Angron next turned his wrath on the Crimson Priests of Sarum, scouring the planet and claiming it as his forward operating base for the next eleven years in a campaign against the Priests remaining empire. Sarum pledged itself to the forces of Horus during the Horus Heresy and became a Forge World for the Dark Mechanicum. During the Heresy, Sarum continued to supply the World Eaters with their armaments.

Towards the later stages of the Heresy, Perturabo himself arrived at Sarum in search of information of where to find Angron. He found the planet corrupted beyond measure, with a solid crust of debris in orbit acting as a type of outer shell. On Sarum, the Priests had become slaves to Chaos, their heads replaced with the skulls of various creatures. At the center of Sarum was a bound Daemon of Khorne known as Sa’ra’am, which revealed that Angron was on the world of Deluge. Sar’ra’am eventually possessed the Iron Warrior Volk, creating the first Obliterator.

Learn More of the Dark Mechanicum


~Guard this knowledge well, lest we suffer the same dark fate as our lost brethren.

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