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Who Are the Space Marine Legions?

The Space Marine Legions were the original twenty massive armies of Space Marines created by the Emperor of Mankind during the Great Crusade. Each legion was led by a Primarch and commanded tens of thousands of genetically enhanced warriors.

QUICK FACTS

ItemDetail
OrganizationSpace Marine Legions
Created ByEmperor of Mankind
Number20 Legions
LeadersPrimarchs
EraGreat Crusade and Horus Heresy

EXPLANATION

The Space Marine Legions were the earliest and largest formations of Adeptus Astartes warriors. Each legion was genetically linked to its Primarch and possessed unique combat doctrines and cultural traits shaped by their leader.

During the Great Crusade, these legions conquered worlds and expanded the Imperium across the galaxy. However, the unity of the legions collapsed during the Horus Heresy when half of the Primarchs betrayed the Emperor and joined Horus in rebellion.

After the Horus Heresy, Roboute Guilliman reorganized the surviving loyalist legions according to the Codex Astartes. The legions were divided into smaller units known as Space Marine chapters to prevent any single military force from becoming too powerful again.

LOYALIST LEGIONS

LegionPrimarch
Dark AngelsLion El’Jonson
White ScarsJaghatai Khan
Space WolvesLeman Russ
Imperial FistsRogal Dorn
Blood AngelsSanguinius
Iron HandsFerrus Manus
UltramarinesRoboute Guilliman
SalamandersVulkan
Raven GuardCorvus Corax

TRAITOR LEGIONS

LegionPrimarch
Sons of HorusHorus Lupercal
Emperor’s ChildrenFulgrim
Iron WarriorsPerturabo
Night LordsKonrad Curze
World EatersAngron
Death GuardMortarion
Thousand SonsMagnus the Red
Word BearersLorgar
Alpha LegionAlpharius / Omegon

Two additional legions and their Primarchs were erased from Imperial records and remain unknown.

WHY IT MATTERS

The Space Marine Legions were the most powerful military forces of the early Imperium. Their division after the Horus Heresy shaped the modern structure of the Adeptus Astartes and influenced the balance of power within the Imperium.

RELATED LORE

Who Are the Primarchs
What Is the Horus Heresy
What Is the Codex Astartes
What Is a Space Marine Chapter

FAQ

How large were the Space Marine Legions?

Some legions contained tens of thousands or even hundreds of thousands of warriors during the Great Crusade.

Why were the legions divided into chapters?

They were split after the Horus Heresy to prevent any single commander from controlling a massive military force again.

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Baron Von Vault Founder & Gaming Systems Analyst
Baron Von Vault is the founder of the Von Vault Network and creator of D4Dead, BorderlandsHQ, and 40KFAQ. He publishes research-driven analysis of action RPG and looter shooter systems, focusing on progression loops, class mechanics, and endgame design.
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