The Treaty of Mars, also called the Treaty of Olympus, was the deal that bound the Imperium of Man to the Martian Mechanicum. Signed in 739.M30, it gave the Emperor the industrial might he needed for the Great Crusade, and it gave Mars a level of independence no other world would enjoy.
What the treaty actually was
It was a diplomatic agreement between the Emperor and the Tech-Priests of Mars. The Mechanicum became a client-state of the Imperium, not a conquered territory. In return for supplying weapons, ships, and war materiel, Mars kept its own laws, its own religion, and its own internal hierarchy.
The Emperor signed it shortly after landing at Olympus Mons. He arrived calling for unity, and he showed off abilities that looked like miracles to the Martian priesthood. He repaired a Knight suit with a touch. That display convinced many Tech-Priests he was the Omnissiah, their Machine God in the flesh.
Why it mattered so much
The Unification Wars had left Terra desperately short of supplies. Mars had the factories, the shipyards, and the knowledge to fix that. The treaty avoided a war inside the Sol System that could have crippled both sides before the Great Crusade even started.
For Mars, the payoff was autonomy. The Imperium agreed not to interfere with the Cult Mechanicus or its internal structure. Any new technology discovered by Imperial forces would fall under Mechanicum jurisdiction. Mars also received support from the Navigators and Astropaths, including six entire Navis Nobilite Houses donated to the red planet.
- Imperium gets: ships, weapons, and industrial output for the Great Crusade.
- Mechanicum gets: religious freedom, political autonomy, and a monopoly on new technology.
- Both sides avoid a costly war in the Sol System.
The bans that shaped tech-heresy
The treaty didn’t just grant freedoms. It also banned certain lines of research. These restrictions became known as the Orders of High Heretechnica. The Emperor used his status as the Omnissiah to lock away subjects the Mechanicum might otherwise have pursued.
The forbidden fields included creating artificial intelligence, deep study of the warp, and manipulation of the human gene-code. Gene-work tied to Primarchs, Custodes, and pariahs was specifically off-limits. On every forge world, anything classed as heretechnica was sealed and restricted. Pursuing it was blasphemy against the Machine God.
How it connects to the wider lore
The treaty is why the Imperium and the Mechanicum are so tightly intertwined. It’s the root of the Adeptus Mechanicus, the Cult Mechanicus, and the tech-heresy that still defines Martian society ten thousand years later.
It’s also why the Emperor is worshipped as the Omnissiah by the Mechanicus, even though the Imperial Creed sees him differently. And it’s the reason the two-headed Aquila became the Imperial symbol, a nod to the alliance between Terra and Mars.
Key facts
- The Treaty of Mars was signed in 739.M30 between the Imperium and the Martian Mechanicum.
- It made the Mechanicum a client-state, giving Mars religious and political autonomy.
- In return, Mars supplied weapons, ships, and technology for the Great Crusade.
- The treaty banned artificial intelligence, warp study, and human gene-manipulation, creating the Orders of High Heretechnica.
- The Emperor was accepted as the Omnissiah by many Tech-Priests after the treaty.
- The two-headed Aquila became the Imperial symbol to honour the alliance.
FAQ
Is the Treaty of Mars the same as the Treaty of Olympus?
Yes. The agreement is known by both names. The Adeptus Mechanicus often calls it the Treaty of Olympus Mons.
When was the Treaty of Mars signed?
It was signed in 739.M30, shortly after the Emperor landed on Mars at the start of the Great Crusade.
Why did the Emperor sign the treaty instead of conquering Mars?
He needed Mars’ industrial base to supply the Great Crusade, and a war in the Sol System would have been devastating. A diplomatic deal was faster and cheaper.