The Second Founding is the moment the nine loyalist Space Marine Legions were broken up into smaller Chapters, right after the Horus Heresy. It reshaped the Imperium’s military and set the template every later Founding follows.
What the Second Founding was
After the Horus Heresy, Roboute Guilliman pushed through the Codex Astartes, a rulebook that capped a Chapter at roughly a thousand battle-brothers. The Second Founding put that rule into practice: each loyalist Legion split into multiple Chapters.
It wasn’t a gentle reorganisation. Legionaries who’d fought side by side for centuries suddenly belonged to different units, often with new names, new colours, and new commanders.
Why it happened
The Heresy proved that one man could turn a Legion against the Emperor. Guilliman and the other loyalist primarchs wanted no single commander to ever wield that much power again.
Splitting the Legions into Chapters made it harder for one traitor to flip a huge force. It also spread Space Marines across the galaxy so a single disaster couldn’t wipe out an entire Legion’s gene-line.
Which Legions were split
The nine loyalist Legions were divided. The Ultramarines, being the largest, contributed the most successor Chapters. The Imperial Fists, Blood Angels, Dark Angels, White Scars, Space Wolves, Iron Hands, Raven Guard, and Salamanders also spawned successors, though some kept closer to their original structure.
The Space Wolves are the famous exception. They resisted splitting and stayed close to Legion strength, which is why their Great Companies look so different from a standard Chapter.
| Original Legion | Notable Second Founding successors |
|---|---|
| Ultramarines | Many, including the Genesis Chapter |
| Imperial Fists | Black Templars, Crimson Fists |
| Blood Angels | Flesh Tearers, Angels Encarmine |
| Dark Angels | Angels of Absolution, Guardians of the Covenant |
| White Scars | Marauders, Rampagers |
| Iron Hands | Brazen Claws, Red Talons |
| Raven Guard | Black Guard, Raptors |
| Salamanders | Few known successors |
How it connects to later Foundings
The Second Founding set the pattern. Every later Founding, from the Third up to the Ultima Founding, creates new Chapters using the same basic structure.
It also explains why the Adeptus Astartes are organised into Chapters instead of Legions. That distinction is the bedrock of Space Marine lore, and it all starts here.
Key facts
- The Second Founding split the nine loyalist Legions into smaller Chapters after the Horus Heresy.
- It enforced the Codex Astartes, which limits a Chapter to about a thousand Space Marines.
- The Ultramarines produced the most successor Chapters.
- The Space Wolves largely resisted the split and kept a Legion-like structure.
- Every later Founding, including the Ultima Founding, follows the pattern set here.
FAQ
When did the Second Founding happen?
Shortly after the Horus Heresy, during the Scouring and the early reform period. It’s the first Founding after the original Legions.
Why are the Space Wolves different?
They refused to fully split into successor Chapters. Their Legion stayed largely intact as Great Companies, which is why they don’t follow the Codex Astartes the way most Chapters do.
How many Chapters came from the Second Founding?
Sources vary on exact numbers, but it produced dozens of new Chapters from the nine loyalist Legions. The Ultramarines alone contributed many successors.