Is it possible for the Imperium to ally with Chaos humans against Craftworld Eldar?

[diadems]

Now out of all the xenos the Imperium has built the closest ties with Craftworld Eldar, and Chaos are the traitors and their worst enemies, though I was wondering about the possibility of the factions aligning along speciesist lines in a particular conflict.

[calgar101]

In the most dire of situations? Possibly but even then very tenuous. You're more likely to have the Imperium ally with Eldar against Chaos.

Some sort of cease fire if Necrons or Tyranids showed up, yes. But allying? No chance.

More than likely the Imperium would fight both enemies even if it expedited their defeat in that theatre of conflict. 

[Grotsmasha]

No. Not unless they want to be executed as Traitors themselves. Chaos is an unacceptable no-no.

[LameBeard]

Whilst I agree with @Grotsmasha and @calgar101, if you wanted to set this up, I would do it as a simultaneous attack on the Eldar, where Chaos wait until the Imperium strikes and then strike alongside. This would be very Alpha Legion (who could even do this as a false flag and appear as Imperial or similar). It could also make sense as part of a Tzeentchian plot. 

[diadems]

58 minutes ago, calgar101 said:

In the most dire of situations? Possibly but even then very tenuous. You're more likely to have the Imperium ally with Eldar against Chaos.

Some sort of cease fire if Necrons or Tyranids showed up, yes. But allying? No chance.

More than likely the Imperium would fight both enemies even if it expedited their defeat in that theatre of conflict. 

 

hmm, just to clarify, what are your thoughts on the idea of a ceasefire if Craftworld Eldar showed up

41 minutes ago, Grotsmasha said:

No. Not unless they want to be executed as Traitors themselves. Chaos is an unacceptable no-no.

 

hmm, though some did put aside their differences to fight against the Orks once in the War of the Beast

[calgar101]

Very unlikely I would say, much more likely to work with the Necrons to fight either Chaos, Tyranids or Necrons.

 

The temporary alliance of Imperial Fists and Iron Warriors didn't go down too well though during the War of the Beasts?

[LameBeard]

So imagine you’re an Imperial Commander, persecuting a war against chaos and in with a chance of victory. You put on a face to the world of hating heretics above all else, but you’re still human. You still want glory, promotion and to keep your backside in one piece to sit down in a comfortable retirement one day. Then these Eldar turn up. An overwhelming and surrounding Eldar force that are clearly intent on wiping you out. So if survival depends on it, just maybe you can write the first draft of history if you get out of this alive and worry about the Inquisitor’s tribunal later. You try a “We’ll be back for you chaos dogs later!” message and see if it’s reciprocated. And cross your fingers you can bring your Space Marine allies and Commissars with you on this one. Maybe the fog of war will give you a fighting chance: you can tell units individually to target Eldar whilst assuring them the reserves are assigned to take out chaos. And a fighting chance  is better than most get in an uncaring galaxy …

[LameBeard]

Just now, LameBeard said:

So imagine you’re an Imperial Commander, persecuting a war against chaos and in with a chance of victory. You put on a face to the world of hating heretics above all else, but you’re still human. You still want glory, promotion and to keep your backside in one piece to sit down in a comfortable retirement one day. Then these Eldar turn up. An overwhelming and surrounding Eldar force that are clearly intent on wiping you out. So if survival depends on it, just maybe you can write the first draft of history if you get out of this alive and worry about the Inquisitor’s tribunal later. You try a “We’ll be back for you chaos dogs later!” message and see if it’s reciprocated. And cross your fingers you can bring your Space Marine allies and Commissars with you on this one. Maybe the fog of war will give you a fighting chance: you can tell units individually to target Eldar whilst assuring them the reserves are assigned to take out chaos. And a fighting chance  is better than most get in an uncaring galaxy …

Obviously does not apply if you are a Space Marine Chapter Master. There is no promotion, there is no comfortable retirement, you wouldn’t like it anyway, and there is no greater glory than dying whilst killing traitors. Also, arguably, you’re not human.

[calgar101]

If logically it would better preserve your force or even mean outright victory against both factions, I don't think a commander would in whatever means align their forces with Chaos to defeat the Eldar. Then if said commander ordered this, how much of the force would then agree?

Blind hatred against Chaos I would say is a bit stronger than hatred for Xenos, so I don't really see it happening, then again the 40k galaxy is a big place as they say.

Perhaps if written well enough it could be done... but there would be consequences. 

[diadems]

1 hour ago, LameBeard said:

So if survival depends on it, just maybe you can write the first draft of history if you get out of this alive and worry about the Inquisitor’s tribunal later.

 

Oh I see, hmm so the idea that I had in mind was more about speciesism, an Imperial commander thinking that CW Eldar might be a worse problem than Chaos humans, as the Imperium also has speciesism and xenophobia.

Edited January 1 by diadems

[diadems]

20 minutes ago, calgar101 said:

Blind hatred against Chaos I would say is a bit stronger than hatred for Xenos, so I don't really see it happening, then again the 40k galaxy is a big place as they say.

Perhaps if written well enough it could be done... but there would be consequences. 

 

And in this case, not just any xenos, but CW Eldar, Asuryanis.

 

And well despite all their betrayal against the Emperor and all the fan-hatred of Erebus lol, I was thinking that the CSM aren't really meant to be some kind of misanthropes

 

I also saw a passage about Horus's nationalism and xenophobia:

 

Quote

The Emperor’s great armies have served their purpose. Now is the time for the Legions to be disbanded and the Space Marines set to other tasks guarding the worlds of humanity and policing the new regimes. The warrior lords that are the primarchs are to become the rulers of worlds and administrators of the Grand Plan.

 

Horus seeks vengeance! He wants to rid the galaxy of mankind’s alien foes utterly. Not a single alien should remain alive to threaten humanity. The Legions must hunt them down and eradicate them all! The glorious armies of the Imperium should not be forced to put down their guns and swords. They must not be emasculated and converted into mere policemen and gatekeepers!

 

[calgar101]

There is a lot of speciesm and hatred of Xenos yes, I'd say that the hatred for Chaos especially those Traitor legions would edge it out. 

I think if it was originally Imperial v Chaos on World X, the arrival of Eldar would not automatically drive the Imperial force to ally with the Chaos forces; say its loyalist guard v traitor guard, both being human would not have the Imperial or Chaos commanders reach any agreement and form Human v Xenos.

 

Possible that Imperial and Eldar team up and destroy Chaos or Possible un easy truce between 2 of the factions to destroy the 3rd? But I think survival of the species here doesn't come into play much and cause Chaos/Imperial temporary co-operation. 

Again there are lots of nuances and factors at play so I am giving a general sweeping answer.

[LameBeard]

1 hour ago, diadems said:

 

Oh I see, hmm so the idea that I had in mind was more about speciesism, an Imperial commander thinking that CW Eldar might be a worse problem than Chaos humans, as the Imperium also has speciesism and xenophobia.

So I think the way to do this is do it backwards: rely on the Eldar’s speciesism. Maybe:

 

You are an Imperial Commander and a true son of the Emperor. You are fighting chaos and you realise you are losing. You are outnumbered, outgunned and out-teeth-and-tentacled. Retreat is unthinkable, even if you wanted to, your superiors would execute you. Only death, torture or slavery awaits you and your force. And all the while, this (much larger) Eldar force nearby look on. Indifferent. Arrogant. Aloof. Are they waiting to finish the loser off? You’ve faced Eldar before. You know that they despise all other races in the galaxy as crude, lower forms of life. They probably regard this fight as no better than Orks. And like Orks, when they stop fighting each other and band together, humans can be dangerous. You will use this to play the Eldar at their own game. You order an attack on the Eldar, letting them know the galaxy is humanity’s birthright, suggesting the upstart Mon Keigh have banded together. The Eldar will not stand for it, they will retaliate with the aim of wiping out every last Mon Keigh. You have assured the destruction of the Chaos host, and likely your own. In the carnage, each unit will react to the new aggressor, such will be their swift attack. And if you manoeuvre correctly, maybe, just maybe, the Chaos force will bear the brunt and the Emperor might  protect the last few of the faithful against a weakened Eldar force.

Edited January 1 by LameBeard

[diadems]

45 minutes ago, calgar101 said:

But I think survival of the species here doesn't come into play much and cause Chaos/Imperial temporary co-operation. 

Again there are lots of nuances and factors at play so I am giving a general sweeping answer.

 

ah ok i see, thanks

20 minutes ago, LameBeard said:

So I think the way to do this is do it backwards: rely on the Eldar’s speciesism. Maybe:

 

You are an Imperial Commander and a true son of the Emperor. You are fighting chaos and you realise you are losing. You are outnumbered, outgunned and out-teeth-and-tentacled. Retreat is unthinkable, even if you wanted to, your superiors would execute you. Only death, torture or slavery awaits you and your force. And all the while, this (much larger) Eldar force nearby look on. Indifferent. Arrogant. Aloof. Are they waiting to finish the loser off? You’ve faced Eldar before. You know that they despise all other races in the galaxy as crude, lower forms of life. They probably regard this fight as no better than Orks. And like Orks, when they stop fighting each other and band together, humans can be dangerous. You will use this to play the Eldar at their own game. You order an attack on the Eldar, letting them know the galaxy is humanity’s birthright, suggesting the upstart Mon Keigh have banded together. The Eldar will not stand for it, they will retaliate with the aim of wiping out every last Mon Keigh. You have assured the destruction of the Chaos host, and likely your own. In the carnage, each unit will react to the new aggressor, such will be their swift attack. And if you manoeuvre correctly, maybe, just maybe, the Chaos force will bear the brunt and the Emperor might  protect the last few of the faithful against a weakened Eldar force.

 

that's an interesting take, though i think that the Eldar would surely be aware that the Imperial commander does not have control over the Chaos forces

Edited January 1 by diadems

[calgar101]

@LameBeard I think you could do what you suggested and manoeuvre forces to draw out attouts against Chaos or Imperial forces, depending who is more canny. That would be quite a scenario to see played out. 

[LameBeard]

15 minutes ago, diadems said:

 

ah ok i see, thanks

 

that's an interesting take, though i think that the Eldar would surely be aware that the Imperial commander does not have control over the Chaos forces

In this worldview, the Eldar word closest to “control” does not translate to human activities in any meaningful way. Does a mould spore “control” its fellows? No, it merely spreads its stain and disfigurement across what is otherwise good and wholesome, just like humanity spreads across the stars that were reserved for the children of Asyr. A vague ”common purpose” or “herd mentality” is all the Eldar commander needs to believe. The Eldar are arrogant. And with arrogance comes pride and complacency. The Eldar could look deeper into the matter, but why do so, when their prejudices appear to have been confirmed?
 

Yes it was a stretch. But it is more fun to play the Eldar with flaws than “Eldrad saw everything coming and was brainier than you and won before the fighting even started”.

Edited January 1 by LameBeard

[Cleon]

I agree, Chaos would be a no, however an unaligned rediscovered human world, or some 'we don't want to pay our tithes an you were sent to punish us but the eldar showed up' semi renegade world perhaps would get re-prioritised to 'deal with you later'.

[kabaakaba]

If you SM there is no chance thought "ally with chaos " can appears in you brain. 

If you Militarum commander the moment you vocalize your thought is the moment when  bolts from commissar, your second-in-command and maybe someone else remove your head.

SoB also no questions. 

Maybe some radical inquisitor who in command right now can do something like this.

[Lathe Biosas]

Space Marine Commanders, Imperial Officers and Inquisitorial Agents use Chaos forces all the time... for knowing where to shoot.

 

"Fire an Artillery Barrage at that cluster of Heretics on Hill 725, Sergeant!"

 

"Sir, if we aim a little to the left, we might hit some of those foul Xenos too..."

 

"Are you questioning my judgment Sergeant?"

 

 

[diadems]

2 hours ago, kabaakaba said:

If you SM there is no chance thought "ally with chaos " can appears in you brain. 

If you Militarum commander the moment you vocalize your thought is the moment when  bolts from commissar, your second-in-command and maybe someone else remove your head.

SoB also no questions. 

Maybe some radical inquisitor who in command right now can do something like this.

 

though i would think that it also depends on the type of external enemy being faced

[kabaakaba]

4 hours ago, diadems said:

 

though i would think that it also depends on the type of external enemy being faced

There is same Imperial cult for many thousands years. No matter which third enemy you have choice always the same you are dead if fight as is or you are dead and damned if you allies with chaos.

[diadems]

23 hours ago, kabaakaba said:

There is same Imperial cult for many thousands years. No matter which third enemy you have choice always the same you are dead if fight as is or you are dead and damned if you allies with chaos.

 

well there is an episode of them allying against Orks during the War of the Beast

[diadems]

On 1/2/2026 at 7:36 AM, Lathe Biosas said:

Space Marine Commanders, Imperial Officers and Inquisitorial Agents use Chaos forces all the time... for knowing where to shoot.

 

"Fire an Artillery Barrage at that cluster of Heretics on Hill 725, Sergeant!"

 

"Sir, if we aim a little to the left, we might hit some of those foul Xenos too..."

 

"Are you questioning my judgment Sergeant?"

 

 

 

hmm that sounds like the idea that Chaos forces and xenos cluster together

[Halandaar]

On 1/3/2026 at 5:39 AM, diadems said:

well there is an episode of them allying against Orks during the War of the Beast

 

Sure, although attributable to a single captain who ended up killing human and Astartes allies and ultimately defected to the Iron Warriors and got his entire chapter disbanded as a result. It wasn't exactly a quick alliance of convenience.

[diadems]

8 hours ago, Halandaar said:

 

Sure, although attributable to a single captain who ended up killing human and Astartes allies and ultimately defected to the Iron Warriors and got his entire chapter disbanded as a result. It wasn't exactly a quick alliance of convenience.

 

well i think its plausible that there could be transactional imperial commanders who could agree to a ceasefire in order to conveniently collectively kick some xenos butt and then just as easily ruthlessly turn on the traitors when they're no longer needed

 

in fact it might be considered that the culture of the Imperium partially fosters transactional attitudes, the notion that the Imperials and Chaos forces are dark reflections of each other, two sides of the same coin.

Edited January 4 by diadems