The Astra Militarum’s regiments are the Imperium’s massed infantry and armour, raised planet by planet and shipped across the galaxy. They’re the backbone of almost every war the Imperium fights, and their homeworlds shape how they look, fight, and die.
What a regiment actually is
A regiment is the standard building block of the Astra Militarum, the organisation most people still call the Imperial Guard. Each one is raised from a single world, given a number and often a nickname, then shipped off to fight somewhere else entirely.
That last part matters. The Imperium deliberately sends regiments far from home so they can’t turn on their own people or build local power bases. A regiment might spend centuries away from the planet that raised it, recruiting replacements from whatever worlds it passes through.
How they’re raised and named
Most regiments carry a number plus a homeworld or founding name, like the Armageddon Steel Legion or the Athonian Tunnel Rats. Some have famous nicknames, and penal legions are drawn from convicts rather than volunteers or conscripts.
Regiments vary wildly in size and role. You’ll find line infantry, armoured regiments, siege specialists, cavalry, abhuman units, and penal battalions. A world’s culture and terrain usually decide what kind of regiment it produces.
Why homeworlds matter so much
A regiment’s character comes from where it was raised. Death worlds breed hardened survivors, hive worlds produce endless waves of infantry, and forge worlds tend to send armour and artillery.
This is why the same army can look completely different from one campaign to the next. A Cadian shock regiment and a Catachan jungle fighter regiment share a chain of command but almost nothing else in style or tactics.
- Armageddon: Steel Legion, mechanised infantry and armour
- Catachan: jungle fighters, stealth and close-quarters brutality
- Cadia: disciplined shock troops, the classic Guard template
- Valhalla: ice-world infantry, stubborn and numerous
- Tallarn: desert raiders, fast and mobile
- Krieg: siege specialists, grim and attritional
How they fit into the wider lore
Regiments sit under the Departmento Munitorum, which handles recruitment, supply, and deployment. Above them are the Lord Commanders and, in theory, the High Lords of Terra.
They fight alongside Space Marines, Adeptus Mechanicus forces, and the Sisters of Battle, but they’re the ones who hold the line in numbers. Most wars in the 41st millennium are won or lost by Guard regiments long before anyone else shows up.
Key facts
- A regiment is raised from one world and usually sent far from it.
- Homeworld culture and terrain shape a regiment’s style and specialisation.
- Regiments include infantry, armour, siege, cavalry, abhuman, and penal units.
- They answer to the Departmento Munitorum and ultimately the High Lords of Terra.
- Named regiments like the Steel Legion and Catachans come from codexes and novels.
FAQ
What’s the difference between the Astra Militarum and the Imperial Guard?
They’re the same thing. Imperial Guard is the older, informal name; Astra Militarum is the official title used in current lore. Fans use both interchangeably.
How many regiments are there?
Effectively countless. The Imperium has millions of worlds, and new regiments are raised constantly. Published lists only cover the ones named in novels, codexes, and campaign books.
Can a regiment fight alongside Space Marines?
Yes, and it happens often. Guard regiments provide the numbers and holding power while Space Marines strike at key targets. The relationship is usually distant rather than friendly.