The Legiones Astartes are the original Space Marine Legions, the Emperor’s genetically engineered armies built for the Great Crusade. When Horus turned on his father, half of them followed him, and that split still shapes the entire 40k setting.
What the Legiones Astartes actually were
During the Great Crusade, the Emperor fielded eighteen Space Marine Legions, each led by a Primarch and numbering in the tens of thousands. They were the Imperium’s main tool for reconquering the galaxy after Old Night.
Every Legion had its own identity: a name, a colour scheme, a preferred style of war, and a set of traditions inherited from its Primarch. The Thousand Sons leaned on psychic power, the World Eaters on close combat, the Iron Warriors on siegecraft, and so on.
The Horus Heresy splits them in two
Horus, the Warmaster, turned against the Emperor, and nine Legions joined him. Those Traitor Legions are the Emperor’s Children, Iron Warriors, Night Lords, World Eaters, Death Guard, Thousand Sons, Sons of Horus, Word Bearers, and Alpha Legion.
The remaining nine stayed loyal. That gives you the classic Loyalist lineup: Dark Angels, White Scars, Space Wolves, Imperial Fists, Blood Angels, Iron Hands, Ultramarines, Salamanders, and Raven Guard.
The war ended with Horus dead and the Traitors driven into the Eye of Terror, but the Legions were never the same. The Loyalist Legions were eventually broken down into the smaller Chapters that make up the Adeptus Astartes of 40k.
How they play on the tabletop
In Warhammer: The Horus Heresy, the Legiones Astartes are the core army. You use the Age of Darkness rulebook for the basics, then pick up Liber Hereticus for the Traitor Legions or Liber Astartes for the Loyalists.
Those books cover unit profiles, wargear, Warlord Traits, Reactions, Rites of War, and Primarch entries, along with painted galleries showing each Legion’s heraldry and colour schemes.
| Book | Covers | Released |
|---|---|---|
| Liber Hereticus | Traitor Legions | 2022 |
| Liber Astartes | Loyalist Legions | 2022 |
What to buy first
If you’re starting out, the Legiones Astartes Battle Group is a solid entry point. It gives you thirty MKIII Space Marines, enough for a full tactical squad plus two Legion Support Squads, along with a Land Raider Proteus, a Deredeo Dreadnought, and a Special Weapons Upgrade Set.
The MKIII and MKVI plastic kits share upgrade sprues, so heavy and special weapons cross over between armour marks. The older plastic Horus Heresy Space Marines don’t fit those upgrades as cleanly, so keep that in mind if you’re mixing in secondhand models.
Key facts
- The Legiones Astartes were the eighteen Space Marine Legions of the Great Crusade, each led by a Primarch.
- Nine Legions turned Traitor with Horus; nine stayed loyal to the Emperor.
- The Traitor Legions are Emperor’s Children, Iron Warriors, Night Lords, World Eaters, Death Guard, Thousand Sons, Sons of Horus, Word Bearers, and Alpha Legion.
- After the Heresy, the Loyalist Legions were broken into Chapters, becoming the Adeptus Astartes of 40k.
- Liber Hereticus and Liber Astartes are the 2022 army books for Traitor and Loyalist Legions respectively.
FAQ
How many Legiones Astartes were there?
Eighteen. Nine stayed loyal to the Emperor and nine turned Traitor with Horus.
Are the Legiones Astartes the same as Space Marines?
They’re the original Space Marine Legions from the Horus Heresy era. After the Heresy, the Loyalist Legions were split into the smaller Chapters that form the Adeptus Astartes in Warhammer 40,000.
Which book do I need for a Traitor Legion army?
You need the Age of Darkness rulebook plus Liber Hereticus. That covers the rules, wargear, and Primarchs for all nine Traitor Legions.