Did every legion fight each other?

[Valkyrion]

In official GW writing (big black books, horus heresy novels, white dwarf etc) how many legions fought* all 9 of their loyalist/traitor counterparts?

 

At my inexpert count, Raven Guard, Iron Hands and Salamanders have fought 8 traitors each (no Thousand Sons) and that's the best score I can come up with, but I will have missed short stories or references or simply forgotten some things. 

 

*By fought I don't mean one hero attacking another hero - I mean like a battle you could recreate on the table top.

 

[N1SB]

That's a good question, Brother Valkyrion.

 

Imperial Fists definitely fought all of them at the Siege of Terra, including iirc about 5,000 Word Bearers that followed Zardu Layak (who had forsaken their Primarch Lorgar in favour of Horus, the true Chosen of Chaos...but he kinda foresaw Abaddon was their real champion in advance) and Alpha Legion who were infiltrating the Imperial Palace, but those were like skirmish forces.  So the Word Bearers and Alpha Legion weren't there in full force, but it's not just isolated characters having duels, these were full military operations.

 

There were, of course, other Loyalists there, so very likely the Blood Angels and White Scars fought most of them except for probably the Alpha Legion as they were so far behind enemy lines.  The small contingent of Salamanders with Vulkan there were mainly defending the Emperor himself, Beloved By All, so they probably didn't fight everyone.

 

Yeah, I know for certain only Imperial Fists, Brother, then probably Blood Angels and White Scars but I'm not fully sure.

[apologist]

Interesting question – thanks for the food for thought!

 

I think it's fair to say that the current lore has the tacit understanding that everyone fought everyone else, making tabletop games between whatever factions you choose at the very least reasonably justifiable.

 

In the context of the question above, however, I imagine that there are going to be a few gaps where there's no 'official' known battles; but we'd have to work through Legion by Legion.

 

So... let's do that! I'll kick off with my favourite Legion, the Battle-Kings of Ultramar; the Ultramarines. Listed below are known events which fit @Valkyrion's requirement for a battle you could recreate on the tabletop. Those marked with an asterisk (*) are arguably post-Heresy, fleet-based, very minor or otherwise unusual.

 

+ Ultramarines +

• Emperor's Children – [None I can find beyond the Scouring-era Thesalla*]
• Iron Warriors – Carchera, Deluge, Tallarn*
• Night Lords – Sotha; Desperation
• World Eaters – Armatura, Nuceria etc.
• Death Guard – Molech
• Thousand Sons – [None I can find]
• Sons of Horus – Molech
• Word Bearers – Take your pick: Calth, Honourum etc.
• Alpha Legion – Serpent's Coil campaign*, Eskrador*

 

... and my current enthusiasm. I've listed Isstvan V only for the Legions that the Legion principally engaged; while World Eaters , Death Guard and Sons of Horus were present, they were distant on the battlefield.

+ Salamanders +

• Emperor's Children – Pale Stars, Erellia, Nyrcon, Pale Stars
• Iron Warriors – Isstvan V, Erellia, Mezoa
• Night Lords – Isstvan V
• World Eaters – [None I can find, except for possibly Tralsak]
• Death Guard – Nocturne
• Thousand Sons – [None I can find]
• Sons of Horus – Dwell*, Aragna
• Word Bearers – Traioris*
• Alpha Legion – Isstvan V, Nyrcon

Edited July 3 by apologist

[Lautrec the Embraced]

Seems to be easier to find such engagement for Isstvan "participants", it nets them a lot of potential enemies. Thousand Sons definitely seems to be the most isolated on the side of traitors. With loyalists - Ultramarines are I think most difficult? rather far away for quite a lot of Heresy, busy with WB and WE, and only then doing more for Scouring. 

 

Nevertheless, I think Sons of Horus fought against basically everyone:

• RG - Isstvan V, Yarant
• IH - Isstvan V, Dwell, Aragna,  mostly as shattered legions
• Sallies - mostly as above as shattered legions; Siege of Baal?
• DA - Advex-Mors
• Ultra - Molech
• SW - Trisolian, Yarant
• BA - Beta-Garmon, Terra
• WS - Beta, Dwell, Terra
• IF - Cthonia, Terra

So, 9/9 accounted for I think, while of course some engagements are of smaller scale than others. I am certain many more battles could be find. 

BONUS - potentially fought 4 loyalist remnants of traitor legion at Isstvan III + sometimes other small scale fights with other loyalists

 

I'd wager World Eaters could also be 9/9, with their presence at Isstvans (3/9), Terra (6/9), Shadow Crusade against Ultramarines (7/9), some action vs Dark Angels within Ultramar (I think?) (8/9) and some forces in Trisolian/Yarant (9/9)

 

Night Lords, I'm not certain - we have Isstvan of course, Terra (though they barely do anything, I don't recall any fights with White Scars for example), they also had large Thramas Crusade against Dark Angels, and attacked Ultramarines' Sotha. Provided they had some some detachments alongside SoH fighting Russ (not inconceivable knowing the state of this legion and the fact they'll be later on Terra), we could just get to 9/9, but it's more forced.

Edited July 3 by Lautrec the Embraced

[librisrouge]

On an official, it is in a novel or rulebook level, I'm inclined to say no. I'd love to see something official in that capacity but that'd take some impressive work.

 

Unofficially, I'd be inclined to say yes. There are a lot of legion fragments and small forces that didn't link up with the larger narratives in the Horus Heresy. These forces did their best to contribute to the war effort in some capacity and likely fought all sorts of foes. 

[LameBeard]

In the very early lore, Horus planned his attack at a time where Johnson and Russ were stranded at the wrong end of the galaxy, implying Dark Angels and Space Wolves didn’t see a lot of action, but then their impending return forced Horus’s hand to open the shields on the Vengeful Spirit and create a showdown.

 

I guess a fair bit of this has been retconned, but, Watch packs aside, are the Wolves the most isolated of the loyalist legions, who have the fewest known traitor opponents?

Edited July 3 by LameBeard

[Urauloth]

On 7/3/2025 at 4:18 PM, Lautrec the Embraced said:

Night Lords, I'm not certain - we have Isstvan of course, Terra (though they barely do anything, I don't recall any fights with White Scars for example), they also had large Thramas Crusade against Dark Angels, and attacked Ultramarines' Sotha. Provided they had some some detachments alongside SoH fighting Russ (not inconceivable knowing the state of this legion and the fact they'll be later on Terra), we could just get to 9/9, but it's more forced.

 

Technically they fought the White Scars during the Thramas Crusade, and so did the Dark Angels. I'm not sure if it counts for the purposes of this thread because it was only a single Brotherhood, but Zhenjin Khan had ~3000 warriors and fought in several full-scale battles for and against both sides, so I think so.

 

Speaking of the 1st, they're a bit hard to keep track of, but here's what I've got from memory:

Emperor's Children: Chemos? Not sure if there was any actual fighting here. EC had mostly abandoned it so I think this was just an exterminatus action.

Iron Warriors: Can't think of anything specific until the Scouring.

Night Lords: Entire Thramas Crusade.

World Eaters: Ultramar, Nuceria.

Death Guard: Barbarus, Perditus, The Astronomicon.
Thousand Sons: I'm not sure they met at all?

Sons of Horus: Advex-Mors technically, but I can't think of anything else specific I forgot about Cthonia

Word Bearers: I'm sure they fought at some point while The Lion was in Ultramar, but I can't think of an example. I'll have to check Angels of Caliban.

Alpha Legion: Alaxxes.

 

As a bonus, legion elements under Luther fought Imperial Fists at Zaramund, and the Lion's contingent fought Zhenjin Khan's aforementioned White Scars at Sedricce and several other worlds in the Thramas sector before they switched sides.

Edited July 6 by Urauloth

[The Scorpion]

If you account for tabletop campaign books, it is pretty much a given that every legion fought every legion.

There is lore about the Dark Angels fighting the Thousand Sons at Zhao Arkkad and lore about a joint force of Thousand Sons and Dark Angels attacking a planet near Beta Garmon

There is lore about the Space Wolves leading the initial spearhead assault to capture Cthonia and lore about a joint warband of Sons of Horus and Space Wolves who lost themselves to bloodlust in the western reaches of the galaxy under a certain captain Skyrar (oddly enough a confirmed origin story for 40k Skyrar's Dark Wolves)

Every combination is possible. Now sticking only to Black Library books? That'd be trickier

[Valkyrion]

In the weeks that have passed since I started this topic, our 3.0 campaign is going to involve Dark Angels, Blood Angels and Ultramarines vs World Eaters, Night Lords and Death Guard.

Was there a theatre of war in which those six fought? 

The Ultramarines might just be a placeholder for now (not starting until christmas and he's thinking of a new legion), so could the Ultramarines be swapped out for a different loyalist legion to make an official warzone involving the other 5 legions + AN Other loyalist?

 

We're perfectly happy to invent something, but if there is a ready made setting available that we could read about it makes things a bit fuller. 

 

[Cleon]

I must admit to not being particularly up on the later stages of the fleshed out HH these days, but unless you are looking at small splinter remnants, the Blood Angel's core legion's heresy pretty much went:
Signus

Ultramar (Imperium secundus)

Beta Garmon

Terra

 

And of those the only one I think had Dark Angels or Ultramarines was Imperium Secundus. Fortunately it had both, and I think World Eaters and Night Lords along with I think mostly Word Bearers. Death Guard might be a little of a stretch, but that's where I'd suggest having a poke around.