This is a proper "musing" article, it doesn't really go anywhere, nor is it trying to make any big points, I'm just thinking about the size, scale and culture of Astartes Legions in 30k.

Prior to the release of the FW Horus Heresy, If I'd been asked to hazard a guess at the size of the various legions, I would have put the Ultramarines at 200,000 or so, the Sons of Horus at 150,000 or so, the Thousand Sons at 10,000 or so, and the rest of the legions at 100,000, give or take.

As it's turned out, there is a far wider distribution of Legion size, with some surprising variants. Here's what we have so far, of the canon FW material, in size order.

1. Word Bearers-Thought immediately prior to Isstvan to be around 140,000, in fact likely much larger:"by some reports their numbers rivalled the ultramarines." No official number given, but likely very large, if they rival the Ultras.

2. Iron warriors-150,000-180,000. I was surprised by this, I'd assumed they'd be a smaller Legion.

3. Sons of Horus-130,000-170,000

4. World Eaters-150,000

5. Alpha Legion-120,000-130,000 (though possibly as Low as 90,000 or as high as 180,000). The level of uncertainty regarding the size of the Legion is a neat touch, and nicely in keeping with their character.

6. The Iron Hands-113,000

7. The Emperors Children-110,000

8. The Night Lords-90,000-120,000

9. Imperial fists-100,000

10. The Death Guard-95,000

11.Salamanders-89,000 (83,000 of which went to Isstvan where they suffered 98% casualties. 2,000-3000 garrisoned major facilities elsewhere, along with a full intake of neophytes and several line companies.)

12. Raven Guard-80,000

So we have 4 broad categories:

Very large legion: 200,000 plus. Likely only the Word Bearers and Ultramarines fall into this category.

Large Legion: 150,000-200,000. At the moment only the iron warriors and world eaters definitely fall into this category, though the sons of Horus probably did too (well, prior to Isstvaan, anyway.) The Alpha Legion might too. I'd hazard a guess that the Dark Angels do, too.

Average legion:- 100,000-150,000. At the moment this would probably cover the alpha legion, iron hands, emperor's children, night lords, and imperial fists. I reckon the space wolves, white scars and blood angels fit into this category, too.

Smaller legion: at the moment only the salamanders and raven guard fall into this category, but I reckon the thousand sons are prime candidates, too.

It's interesting to compare these legions with the size of various modern armies:-

British army:- 125,430 (exc reserves)

US Army: 546,047 (exc reserves)

German army: 62,279

French army: 119,070

Australian army: 30,235

Russian army: 285,000 personnel incl est 80,000 conscripts

Like I say, this post doesn't really go anywhere, but I think it is interesting to think of Legions being so much larger than many modern militaries. I think there is still a tendency to see Legions as pretty much the same as the Chapters that replaced them; in many sources (particularly the HH novels) we see "Captains" and "companies" treated as the standard subdivisions for the Legion as if we were dealing with a Codex Chapter. Whilst some Legions clearly preferred not to operate in this way, when one compares this to, say, the British Army, (which is about the same size as a larger Legion) it's clear that there are massive cultural and structural differences between different ranks and between different parts of the same army. In many ways I think that the image painted of Legion structure within the HH novels is too simplistic; the FW books have a far more interesting take on them, in my opinion.

The legions are massive and independant. Each legion has the supplies,firepower and men to be an empire in its own right. Imagine it this way, betraying the imperium can be quite lucrative, if you don't get caught. I agree with that the FW books have them more interesting than the HH books. I also like it how you made four catogories because it works and is correct. Though I am surprised that the World Eaters are in the large category. I would have thought that their tactics of cgarging the enemy would cost them. Any agreements in that?

Also - bear in mind one key element; those numbers don't include serfs, helots, non-astartes ship crews, servitors, etc, etc.

Almost every one of those hundred thousand astartes is a trigger-puller, whereas in a modern nato-standard army, you often get a 7-10:1 divisional wedge - meaning of those five hundred thousand US army personnel, you've got just over sixty thousand people with a rifle, tank or whatever whose primary job description is "shoot at stuff".

To translate, in some putative invasion of contemporary earth, the larger legions outnumber the US army in primary combatants 3-1 as well as being Astartes fighting normal soldiers. Add in the supposed 10-1 edge of astartes (a hundred marines or a thousand other troops) and a legion would quite realistically take earth's combined militaries in a 'fair' fight.

Note that I can't see the Legions being massively more efficient in divisional wedge - an astartes infantryman is a resource and maintenance intensive asset between his high-tech armour and weapons, larger appetite, the fact that you're projecting power across star systems rather than continents, and the Imperium's general preference for throwing manpower at a problem until it goes away.

I wouldn't be surprised to see a divisional wedge half again or even twice that of a modern army (20:1), which means that to put fifty odd thousand marines on the field, the crusade fleet would be carrying a million personnel.....

Every legion structures itself a bit differently, but yes, there are a couple of tiers; Grand Companies, Hosts or Chapters are as big (or bigger) than 40k chapters, and their commanders are massively important individuals.

Note that the black library books sometimes use the phrase 'line captain' to identify someone commanding 100 astartes as opposed to someone commanding a grand company.

Good points, Grendel. I agree that the support staff element is likely to be enormous. This isn't well reflected in the HH books generally, in my view. I think a lot of the HH writers still subconsciously think in terms of Legions as just being a different title for a Chapter, and write from that perspective. Really a Legion is akin to a small nation state in terms of overall population.

And as for the World Eaters, Misha, I agree it's a little surprising to see them with such a large Legion.

However, I suppose that for both the World Eaters and Death Guard one gets the feeling that their Primarchs were pretty brutal with their own marines, and were quite content to incur enormous casualties when it suited them. One imagines that the "support staff" element of each Legion would have been pretty experienced at recruiting neophyte marines at high speed to recover losses; as such perhaps the populations of these two legions varied widely over relatively short periods to reflect massive casualties and massive recruitment drives. The Death Guard being at 95,000 and the World Eaters being at 150,000 suggests that perhaps they just happened to be at opposite ends of this normal cyclical process at the time of Isstvaan. Perhaps the "normal" size for each Legion was more in the region of 122,500 to split the difference between these two extremes. This would put both Legions in the "average" category. No canon support for that theory, obviously, though.

...Digging through some old white dwarfs specifically the 4th edition marine codex release one:

"A chapter is a thousand marines but has maybe forty thousand support staff"

Ouch. Make that 40:1. That means a 100,000 strong 'generic' legion requires the population of New Zealand to keep it in the field.

And in military force reckoning, 100,000 field troops is equivalent to a 1,000,000 'army' - and if 10-1 because of the improved fighting power of astartes, that's a 10,000,000 strong army - or the combined military strength of the USA, Russia and China.

...Digging through some old white dwarfs specifically the 4th edition marine codex release one:

"A chapter is a thousand marines but has maybe forty thousand support staff"

Ouch. Make that 40:1. That means a 100,000 strong 'generic' legion requires the population of New Zealand to keep it in the field.

And in military force reckoning, 100,000 field troops is equivalent to a 1,000,000 'army' - and if 10-1 because of the improved fighting power of astartes, that's a 10,000,000 strong army - or the combined military strength of the USA, Russia and China.

Comparing it to modern day terra is amusing...there is no doubt in my mind that if the emperor rolled out a half a million thunderwarriors today...The world would be brought to heel before too long.

Remember, a whole planet is dedicated to supporting the few thousand astartes. The UM have a whole sector at the start of the heresy. If you include the support personal into the legion along the same lines as modern militaries each legion would be in the billions.

The UM have a whole sector at the start of the heresy.

I've never seen the source for the "sector", but in GW's own studio material, it is eight star systems with a total of 9 inhabited worlds (8 after the 'nids wrecked Prandium).

I'm guessing this may be a case of contradictions with some novel, or simply internet hearsay (which is quite strong and diverse when it comes to 40k, apparently, specifically because there is so much conflicting information even from official sources - the usual community-based game of "Chinese whispers" only amplifies this further).

Note: Due to the peculiar way of how this IP works, treating Ultramar as a sector is not really "wrong" - I just thought it should be pointed out that this seems to be a personal assessment rather than something put forth in the books.

Alternatively, Ultramar could simply be classified as a sector in a political sense (meaning, based on who rules those worlds) rather than geographical, much like how Hong Kong is both a city as well as its own administrative region in the PRC. If there is a conflict between sources, I suppose this is how I'd try to "merge" them, if I wanted to adapt both to my own vision of the setting.

...Digging through some old white dwarfs specifically the 4th edition marine codex release one:

"A chapter is a thousand marines but has maybe forty thousand support staff"

I admit the number shocked me at first, but the more I think about it, the more sense it makes. After all, almost every Chapter has its own fleet of starships, and all of them are crewed by Human serfs, the combined number of whom could easily surpass the amount of people inhabiting the Fortress Monastery (most of whom may be Servitors).

Ironically, the Space Marines are both the core as well as the smallest part of their own military machine even where offensive capabilities are concerned, depending on how much value you place on, say, the firepower of a Strike Cruiser.

Myself, I've not really decided how big exactly I would envision the Legions. A few years back, there seems to have been a shift that increased their size about tenfold from ~10.000 to 100.000, but I have to say I'm still drawn to the smaller number as it seems to be more in line with the older, but studio-written Index Astartes and its article on how the Legions split into Chapters, or how the increasingly aggressive recruitment practices of the Ultramarines supposedly had them supply more than half of all active Astartes in the years following the Heresy shortly before the Legion was split up (into 23 Chapters, suggesting they were at ~23.000 during this period, whilst all other Legions transformed into 1-5 Chapters each, suggesting 1.000 to 5.000 surviving Loyalist Marines per Legion).

The maths just sound more reasonable to me this way, but a lot of this admittedly hinges on how horrible we think their casualties throughout the Heresy were. To me, 50%-90% just seems more sound than the alternative of 95%-99%, even if the Heresy saw some pretty bad battles.

Ultimately, of course, there is no "right" answer, as even the official sources are intentionally contradicting themselves. For what it's worth, the currently most popular interpretation seems to be Black Library's Horus Heresy novel series, and I believe this one is pushing the 100k idea.

Quick Math note Lynata, but 23 Chapters is only 23,000 Astartes. You put 230,000

Quick Math note Lynata, but 23 Chapters is only 23,000 Astartes. You put 230,000

****, seems I wasn't quick enough with the edit.

Fixed already, but thanks either way!

As to Ultramar being a sector, this is an idea being pushed by the HH novels. They call it the "500 worlds". It seems Ultramar is evolving from 9 worlds in total to those 9 worlds being effectively subsector capitals of a vastly larger region. At 500 worlds, it's twice the size of a normal Imperial Sector. It's a logical idea in my book. Ultramar as a distinct super rich and organised region envied by the wider Imperium makes very little sense if it's less than half the size of a typical subsector.

As to the marine legion size, I think the Forgeworld books are the ones putting the most detail into Legion size, but I think that is based on the HH books again. Don't quote me on this, but I think one of the early books (maybe Horus Rising) cited the Ultramarines as being circa 250,000 strong. I think that this was the first concrete figure cited for a legion, and it all seems to have flowed from there.

I wonder if anyone realised that the Ultramarines are the biggest modern chapter in 40K. Why? Cause the Ultramarines control their own little empire that has its own regiments. Sure they can find an excuse but in the fluff it says that the Regiments from Ultramar are loyal firstmost to the Ultramarines. My friend who runs OW told me that one of his players is from a custom regiment that come from Ultramar. He said it was legit. Most of us agreed, because it did make sense but it did cause drooling stares at Space Marines.

As to Ultramar being a sector, this is an idea being pushed by the HH novels. They call it the "500 worlds". It seems Ultramar is evolving from 9 worlds in total to those 9 worlds being effectively subsector capitals of a vastly larger region.

Ah! Thanks for clearing this up - I really thought this was just something someone made up, and it got repeated so often that it took on a life of its own. Unfortunately, that tends to happen a lot.

I suppose in those novels the worlds that share the same sun in studio fluff are "ripped apart" and become their own systems then, too?

Ultramar as a distinct super rich and organised region envied by the wider Imperium makes very little sense if it's less than half the size of a typical subsector.

Ah, only if the people of the Imperium would actually have access to a galaxywide network of fact-based information/education outlets. The way I see it, the reputation of Ultramar is largely based on hearsay and propaganda, much like that of the Space Marines themselves. Or any other Imperial institution.

Certainly, it has an element of truth at its core, but considering the distribution of information amongst Imperial citizens (which is very, very limited), I'm leaning towards a mixture of exaggeration, and a focus on the idea of Ultramar ("prosperous, productive planets where honest toil and virtue are rewarded") more than its geographical expansion.

Macragge = 40k's Camelot, if you will.

Still, it remains a matter of preferences and interpretation, so there's no need to adopt another perspective!

I wonder if anyone realised that the Ultramarines are the biggest modern chapter in 40K. Why? Cause the Ultramarines control their own little empire that has its own regiments.

I think this is fairly established in the fandom! Though those regiments tend to get (unfairly, imho) forgotten in the face of "supersized" Chapters such as the Black Templars or Space Wolves.

Not entirely. The "Realm of Ultramar" in the Horus Heresy is a lot bigger than the Ultramar ( _{sector?) in M.41, which I didn't think was a single system (may be wrong) but was a very small region of space.}

_{We don't know exactly what happened because we've not 'seen' the scouring yet, but:}

_{Firstly, Angron and Lorgar have killed a lot of those worlds, including the Legion's primary training facility (and no, that wasn't Macragge - it is now, but at the time that was the administrative capital and legion headquarters, not the 'academy')}

_{Secondly, they were no longer under the Legion's governance in the millenia after the heresy because there wasn't a legion to govern them - each primary world was governed by a senior Legion commander, and when the Legion was broken up, "Ultramar" was probably split up too - 'chapters' are Ultramarine grand company equivalents - when the legion was split up, the local command centre where a chapter was stationed would have become its new homeworld and the local area ceased to answer to macragge.}

_{For reasons relevant to Unremembered Empire, Gulliman would have been keen to divest himself of any claims to rulership of large areas of territory, especially since there would have been a general distrust of any primarch or marine at that point, and direct regional rule would have been handed over to (or demanded by) the Administratum.}

_{I wonder if anyone realised that the Ultramarines are the biggest modern chapter in 40K. Why? Cause the Ultramarines control their own little empire that has its own regiments.}

_{I think this is fairly established in the fandom! Though those regiments tend to get (unfairly, imho) forgotten in the face of "supersized" Chapters such as the Black Templars or Space Wolves.}

_{Indeed. The Defence Auxillia are essentially guard regiments (theoretically they're PDF but they're trained and equipped to very high standards). Which of course means they can't take orders from astartes - that's forbidden by the laws put in place at the close of the heresy. Their line of command runs back to the subsector command and Lord Macragge.....who happens to look suspiciously similar to the Ultramarines Chapter Master but is a legally distinct individual. Honest.}

_{For that matter, the worlds of Ultramar have mechanicus contingents based on them (albeit none of them are forge worlds per se). In addition to the defense auxillia, there was also the Legio Praetor involved in the defence of the Polar fortresses, who also tend to get ignored.}