Deimos is a forge world that isn’t a planet at all. It’s a moon of Mars that got yanked out of its orbit and parked next to Titan, where it quietly builds most of the Grey Knights’ guns, armour and ship ordnance.
What Deimos actually is
Deimos started life as the outer moon of Mars. During the Horus Heresy, when Malcador the Sigillite was putting the Grey Knights together, it was shifted across the Sol System using hidden arcane tech and re-anchored around Titan. Titan itself orbits Saturn, so Deimos is now a moon of a moon.
It sits in the Sol System, Segmentum Solar, and counts as a Forge World of the Imperium. Its tithe grade is Aptus Non, which is the paperwork way of saying it doesn’t pay standard tithes, because everything it produces already goes to a very specific customer.
What it makes for the Grey Knights
Deimos is the Chapter’s main supplier. Its subterranean halls turn out ammunition, armour and equipment, from psycannons to Land Raider components to ordnance for starships. If a Grey Knight is firing it or riding in it, there’s a decent chance Deimos built it.
The moon also holds STC imprints covering the whole canon of Adeptus Mechanicus lore, plus designs for weapons nobody’s thought of yet. The big exception is Nemesis Force Weapons, which the Chapter’s own Techmarines craft back at the Fortress Monastery.
- Psycannons and other heavy infantry weapons
- Land Raider components and vehicle parts
- Starship ordnance
- STC imprints for the full Adeptus Mechanicus canon
- Not made here: Nemesis Force Weapons
Why the secrecy matters
Both sides here are guarding secrets from each other. Deimos ships its gear out using dull-minded Servitors whose memories get scrubbed once the job’s done. That keeps Grey Knights arcana away from the Adeptus Mechanicus, and keeps Mars’ more dangerous knowledge away from the Chapter.
It’s a neat arrangement, and a paranoid one. Neither faction fully trusts the other with what it knows.
Who defends it
Deimos has its own Skitarii garrison plus three Knight Houses, including House Steel. Most of the time they stand guard over the forges. Occasionally they march out alongside the Grey Knights instead.
Deimos patterns
Deimos lends its name to a family of wargear and vehicle patterns used across the Imperium. The best known are the Deimos-pattern vehicles, which show up in Horus Heresy-era army lists.
| Pattern | What it is |
|---|---|
| Deimos-pattern Rhino | Armoured transport |
| Deimos-pattern Predator | Main battle tank |
| Deimos-pattern Vindicator | Siege tank |
| Deimos-pattern Whirlwind Scorpius | Artillery tank |
| Deimos Mk VIa / VId rebreather | Respirator gear |
Key facts
- Deimos is a moon of Mars that was moved to orbit Titan during the Horus Heresy.
- It’s classified as a Forge World of the Imperium with an Aptus Non tithe grade.
- It supplies the Grey Knights with ammunition, armour, vehicles and starship ordnance.
- It holds STC imprints for the entire Adeptus Mechanicus canon.
- Its defenders include Skitarii and three Knight Houses, among them House Steel.
- Servitors with scrubbed memories handle transfers to keep secrets on both sides.
FAQ
Is Deimos a planet or a moon?
It’s a moon. It originally orbited Mars, then got relocated to orbit Titan during the Horus Heresy. Titan is itself a moon of Saturn, so Deimos is a moon of a moon.
Why did the Grey Knights get their own forge world?
Malcador moved Deimos to Titan so the new Chapter would have a dedicated, secure supply line. It builds their ammunition, armour, vehicles and ship ordnance, away from prying eyes.
Does Deimos make Nemesis Force Weapons?
No. Those are made by the Grey Knights’ own Techmarines at their Fortress Monastery. Deimos handles everything else.
Who guards Deimos?
Skitarii defenders and three Knight Houses, including House Steel. They mostly garrison the forges but sometimes deploy with the Grey Knights.