The Ultramarines are the most famous Space Marine Chapter in Warhammer 40,000, and the model every other Chapter is measured against. Sons of Roboute Guilliman, keepers of the Codex Astartes and defenders of the realm of Ultramar, they have fought at the centre of the Imperium's history for ten thousand years. Here is their story.
Army guide, last updated November 4, 2026. Lore summarised in our own words from Black Library novels, codexes and community wikis. For game rules, use the official codex or the official app.
The Ultramarines in 30 seconds
| Who | The XIIIth Legion of the original Space Marines, now a Chapter |
| Primarch | Roboute Guilliman, now returned as Lord Commander of the Imperium |
| Home | Macragge, capital of the five hundred worlds of Ultramar |
| Chapter Master | Marneus Calgar |
| Famous for | The Codex Astartes, discipline, the Battle of Macragge |
| Colours | Deep blue armour with gold and white |
Guilliman and the birth of Ultramar
Like all twenty Primarchs, Roboute Guilliman was scattered across the galaxy as an infant. His capsule landed on Macragge, where he was found and adopted by Konor, one of the world's two consuls. Guilliman grew into a genius of war, government and logistics. When rebels murdered Konor, Guilliman crushed the uprising and became ruler of Macragge.
By the time the Emperor arrived, Guilliman had already built a small, ordered, prosperous empire. When he took command of the XIIIth Legion, he grew that realm into Ultramar, a network of around five hundred worlds that was a model of how the Imperium should work. The Ultramarines became the largest Legion of the Great Crusade, famous for conquering worlds and then leaving them better governed than before.
Marneus Calgar in gold and blue armour" loading="lazy">Betrayal at Calth
When Horus rebelled, his first great stroke against the Ultramarines came at Calth. The Ultramarines had been ordered to gather there alongside the Word Bearers Legion, supposedly to prepare for a joint campaign. Instead, the Word Bearers launched a surprise attack, turning their guns on their "brothers" and unleashing daemons and a corrupted star that scorched the planet's surface.
The Ultramarines lost huge numbers but refused to break. The survivors fought on for years in the tunnels beneath Calth, the so-called Underworld War. Calth became a symbol of the Legion's resilience, and a grudge against the Word Bearers that has never faded.
Imperium Secundus
Cut off from Terra by warp storms and believing the Emperor might have fallen, Guilliman made a controversial decision: he founded Imperium Secundus, a "second Imperium" centred on Macragge, ready to carry on humanity's cause if Terra had fallen. When the truth became clear, he abandoned the plan, but the episode still haunts him, a reminder of how close he came to crowning himself.
The Codex Astartes
After the Heresy, Guilliman understood that the Legions, each tens of thousands strong, were too dangerous: one traitor Primarch could turn an entire army against the Imperium. He wrote the Codex Astartes, a vast book of tactics, organisation and doctrine, and used it to break the Legions into Chapters of around a thousand warriors.
Because the Ultramarines were so large, they gave rise to more successor Chapters than any other Legion. Many of the Imperium's Chapters descend from Guilliman's gene-seed, and many still follow the Codex to the letter. That is why the Ultramarines are seen as the "standard" Space Marines.
Guilliman falls
Guilliman continued to lead the Imperium after the Heresy, until he faced the daemon prince Fulgrim, his traitor brother. Fulgrim struck him with a poisoned blade. Rather than let him die, the Ultramarines placed their Primarch in a stasis field in the Temple of Correction on Macragge. For ten thousand years, pilgrims visited his frozen body, and it was said his wounds were slowly healing.
The Battle of Macragge
The Ultramarines' darkest modern hour came when Hive Fleet Behemoth, the first great Tyranid invasion, struck Ultramar. Under Chapter Master Marneus Calgar, the Chapter fought a desperate defence of Macragge. The Ultramarines' entire First Company of Terminator veterans died holding the polar fortresses, and Calgar himself was badly wounded, but the swarm was defeated. The memory of that sacrifice is honoured in the Chapter to this day.
The Primarch returns
As the Imperium collapsed into the chaos of the Great Rift, Guilliman was finally revived and stepped out of stasis into a galaxy far darker than the one he remembered. He became Lord Commander of the Imperium, launched the vast Indomitus Crusade and brought a new generation of warriors into the fight: the larger, stronger Primaris Space Marines. Marneus Calgar himself crossed the dangerous "Rubicon Primaris" to become one of them.
Famous Ultramarines
- Roboute Guilliman: the Primarch, statesman and general, now the most powerful figure in the Imperium after the Emperor.
- Marneus Calgar: Chapter Master and Lord of Macragge, hero of the Tyranid wars.
- Varro Tigurius: Chief Librarian and seer, haunted by visions of the future.
- Ortan Cassius: the Chapter's ancient, scarred Chaplain and Tyranid-hater.
- Cato Sicarius: the proud, brilliant Captain of the Second Company.
- Uriel Ventris: Captain of the Fourth Company, star of a much-loved series of novels.
- Sergeant Telion: a legendary Scout sniper and teacher.
Black Library books to read
- Know No Fear (Dan Abnett): the betrayal at Calth, one of the best Horus Heresy novels.
- Dark Imperium (Guy Haley): Guilliman returns to a ruined galaxy.
- The Ultramarines omnibus (Graham McNeill): the adventures of Uriel Ventris.
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Find them as Black Library paperbacks and audiobooks.
Collecting Ultramarines: a quick guide
Ultramarines use the full Space Marines range, so every Space Marine kit works for them. They're a balanced, forgiving army: tough infantry, tanks, Dreadnoughts and strong characters like Calgar and Guilliman himself. Start with: a Space Marines Combat Patrol, or the discounted Christmas Battleforce.
How to paint Ultramarines
- Prime with a blue spray, or Macragge Blue over a dark primer.
- Wash the recesses with Nuln Oil or a dark blue shade.
- Paint trims gold (Retributor Armour), eye lenses red, and purity seals bone and red.
- Edge-highlight the blue with Calgar Blue for crisp armour.
Latest Ultramarines news
New to the hobby? Start with our Warhammer beginner's hub, and see the other army guides.
Sources
- Warhammer Community warhammer-community.com
- Games Workshop: Warhammer 40,000 warhammer.com
- Lexicanum: Ultramarines wh40k.lexicanum.com