The Realm of Ultramar is the Ultramarines’ own pocket empire, roughly five hundred habitable worlds in the eastern Imperium, all answering to Macragge. Most Chapters get one planet. The Ultramarines got a sub-sector the size of a small civilisation, and it’s one of the wealthiest and best-run regions humanity has left.
What Ultramar actually is
Ultramar sits in the Ultima Segmentum, on the southern edge of the Eastern Fringe, south of the T’au Empire. It’s one of the furthest realms from the Astronomican, which makes its stability all the more unusual.
It’s often called the Five Hundred Worlds, and that’s meant literally: about five hundred inhabited planets, more than five hundred on a map. The Imperium treats it as quasi-autonomous, an empire within an empire, with the Ultramarines running the place rather than merely recruiting from it.
The five sectors
Ultramar is split into five sectors: North, South, East, West and Centre. Four are overseen by a Tetrarch appointed by Roboute Guilliman, each based on a capital world. The central sector answers directly to Macragge and its lord, Marneus Calgar.
The Tetrarchs aren’t always Ultramarines. Guilliman deliberately drew on other Chapters for some posts, which keeps the realm tied to the wider Imperium rather than to one Chapter’s politics.
| Sector | Base world | Tetrarch |
|---|---|---|
| Northern | Konor (Forge World) | Severus Agemman, First Captain of the Ultramarines |
| Southern | Andermung | Portan, Second Captain of the Genesis Chapter |
| Western | Protos | Balthus, Captain of the Doom Eagles |
| Eastern | Vespator | Decimus Felix, Eleventh Captain of the Ultramarines |
| Central | Macragge | Marneus Calgar, Lord Macragge |
Worlds worth knowing
Macragge is the capital and the heart of the realm, home to the Ultramarines’ fortress-monastery and the seat of the Master of Ultramar. Around it sit the sector capitals and a long list of lesser worlds that keep the whole thing fed, armed and crewed.
The Eastern Sector used to be built around the Sotharan League, until Hive Fleet Kraken destroyed Sotha. Guilliman rebuilt what was left of the league around Vespator, and it now covers roughly 86 planets.
- Macragge: capital, Chapter home world, seat of the Lord Macragge.
- Konor: Forge World anchoring the north and its industrial output.
- Andermung and Protos: sector capitals for the south and west.
- Vespator: rebuilt capital of the east after Sotha fell to Kraken.
- Sotha: a former league capital, lost and not recovered.
Why it matters
Ultramar is what happens when a Space Marine legion gets handed a region instead of a fortress. It has its own defence fleet, its own auxilia, its own chain of command under a Council of Greater Ultramar, and a level of day-to-day order most Imperial worlds never see.
That prosperity shows in blunt numbers. Before recent disasters, average human life expectancy in Ultramar reached the mid-thirties, which in 40k terms is close to a paradise. It’s also why the realm keeps drawing attention: it’s rich, it’s organised, and it’s far from Terra.
Key facts
- Ultramar is a quasi-autonomous realm of the Ultramarines within the Imperium, not a single Chapter world.
- It’s called the Five Hundred Worlds because it contains roughly five hundred inhabited planets.
- The capital is Macragge; Roboute Guilliman is Master of Ultramar and Marneus Calgar is Lord Macragge.
- It’s divided into North, South, East, West and Centre, with four Tetrarchs over the outer sectors.
- It sits in the Ultima Segmentum near the Eastern Fringe, south of the T’au Empire and far from the Astronomican.
- Average life expectancy reached the mid-thirties before recent disasters, unusually high for the setting.
FAQ
How many worlds are in the Realm of Ultramar?
Roughly five hundred inhabited worlds, which is where the nickname the Five Hundred Worlds comes from. The exact count shifts as worlds are lost or reclaimed.
Who rules Ultramar?
Roboute Guilliman is Master of Ultramar, with Marneus Calgar as Lord Macragge running day-to-day rule from the capital. Four Tetrarchs handle the outer sectors, and a Council of Greater Ultramar sits above the whole structure.
Is Ultramar part of the Imperium?
Yes, but it’s quasi-autonomous. It’s an Imperial region that governs itself under Ultramarines leadership, which is why people call it an empire within an empire.
What happened to Sotha?
Hive Fleet Kraken destroyed it. Guilliman reconstituted what remained of the Sotharan League around Vespator, which became the Eastern Sector’s capital.