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How do!

Another thought that’s been rattling around in my pea sized quagmire of a brain for the past few weeks. And now is the time to squeeze that boil and let it’s concentrated Thinks all over the Internet.

And it’s to do with just how important Primaris being Primaris might’ve proven, at least in their first engagements.

See, the Galaxy is overall a pretty stagnant place. Indeed, it’s their lack of stagnation which makes Tyranids and Tau a particular if not outright disproportionate threat. In their own ways, each learns from its experience and innovates to overcome identified deficiencies. So just as their foes thinks they’ve got it figured out? Whoops, here’s some Novel Death For You. Made all the more shocking for their foes because….nobody else really does it.

Then came Primaris. Not only are they a cut above Firstborn Marines, but they’re that rarest of things. Imperial Innovation.

Put yourself, if you will, in the shoes of a Chaos Lord. You’re a survivor of the Long War, and may even have met your own Primarch before Heresy occurred. For 10,000 years, whilst you’ve still had to pick your battles with some level of care? You could pretty much accurately predict not just how the loyalist lapdogs would react, but what they’d react with. Suddenly? WTF? Is that a Landraider? Nah. Can’t be. It’s all…floaty. And the guns are in the wrong place. Oi, Brother Kenny? Brother Kenny? Oh. I’m sure Brother Kenny had a head a second ago.

You vox the rest of your forces. They draw up their battle line comfortably outside of long known small arms range….and receive volley after accurate volley for their trouble. Some fall, the armour of others holds. Clear sign of a jump pack equipped foe is closing the distance. You brace for HTH. You like HTH. It’s super fun. Hold on. Why is it raining plasma bolts? OOOH CRIKEY WHAT THE FLIPPING HECK IS GOING ON???

Novelty. You suddenly, for the first time in what at this stage might as well be forever, have encountered Stuff You Don’t Recognise From A Foe You’ve Specialised In Slaughtering For The Past 10,000 years or so. And that’s allowed the Loyalist Gimps the initiative. All the combat experience in the Galaxy can’t save you if your foe outranges you. Maybe, just maybe, you feel the merest thrill of panic. The fear of rote becoming rout.

Essentially, the Primaris were entirely new. Nobody had seen anything quite like them. They’re using some well known tactics of course, they are Marines at the end of the day. But in those most early engagements, they’re using exotic and entirely unknown weapons against you. Their grav vehicles may allow them to attack from a quarter no tracked vehicle ever could. And in the time it takes you to react and, more importantly, adapt? You could very well wind up all dead and full of holes with your legs up a tree and your head rather annoying gone under the sideboard.

That novelty is a powerful weapon.

At least, that’s my own Chinny Reckon on it. What about you Dakka? Are you nodding in agreement, or have I given your chin a nasty itch?

For a while sure, that is, if the enemy in question even cares.

The bigger issue with the Primaris was that as they started fighting, it became very obvious that they sorely lacked any sort of actual combat skill. They only knew simulations and while that accounted for some success alongside their natural prowess, the casualties of many engagements during the opening of the Indomitus Crusade among the Primaris ranks were staggering. Ascending Firstborn into the Primaris ranks helped stem this tide by placing experienced officers into the command structures of Chapters and Companies.

Of course, by the later years of the first phase, the remaining Mars Born Primaris were all combat veterans but had also been heavily reduced in number with most new Chapters being created from fresh recruits.

I suspect it’s a slip of the keyboard, but I’d say it’s combat experience they lacked, not combat knowledge.

Sorry if this seems nitpicky, but given how controversial Primaris remain I think keeping to (in my own opinion only!) more accurate wording will help the thread.

Certainly I think there’s gonna be a certain Two Way Street here. But, I’d still argue the lane of that heading toward the Chaos Marines has the wider lanes.

Whilst one can never truly know what to expect of Chaos (clue is in the name), for a foe as utterly stagnant and “by rote” as The Imperium, to find that foe suddenly freshly equipped and using new (not the same as competent) tactics and strategies could well catch someone flat footed.

To deliberately over egg this pudding? Consider Napoleon and his indisputable strategic nous, and introduce say, a couple of squads of SAS.

The numbers would almost certainly see this new variable taken out in due course. But the initial mess might very well be a decisive factor in a given battle.

Shrug. From a player point of view primaris are a big deal because their fluff is stupid, their models are replacing older kits and driving them out of production, their rules have a huge impact on the game, etc. From an in-universe point of view they're a complete non-issue. They're marines in power armor with bolters, nothing more. I'm sure the intelligence services of the Imperium's enemies were careful to document and analyze the new equipment but for the troops on the ground they're all the same, primaris marines are no different than MkIV and MkV armor on a tactical squad.

Consider Napoleon and his indisputable strategic nous, and introduce say, a couple of squads of SAS.

Except that's not what primaris marines are. It's more like looking at WWII and asking how differently things would have gone if the US had replaced their M1 Garands in .30-06 with the modern .308 conversion. Is it technically a difference? I guess. Does it matter in one of the most one-sided wars in history? Nope.

 Mad Doc Grotsnik wrote:
I suspect it’s a slip of the keyboard, but I’d say it’s combat experience they lacked, not combat knowledge.

Sorry if this seems nitpicky, but given how controversial Primaris remain I think keeping to (in my own opinion only!) more accurate wording will help the thread.

Yeah, which is why I specified skill, not knowledge. The Primaris had theoretical knowledge of every foe of the Imperium but they had no practical experience in combating them. They had no combat skill beyond basic "programming" as it is, which caused them high casualties when they couldn't adapt to new situations as rapidly as Firstborn could.


Again it all comes back to the enemy caring in the first place.

For Chaos Astartes specifically, showing weakness is unthinkable, unless it's part of the plan if you're a Night Lord or Alpha Legionnaire.

If new Astartes start popping up, the best thing they can do is to challenge them, not just to keep their standing with their followers but to prove to the Gods, or even just themselves, that they are the true Astartes. It's also a common belief, among the Traitor Legions especially, that Loyalists are weak-blooded downgrades of those warriors who conquered the stars during the Crusade and an insult to the legacy of those proud Legions.
I'd argue that many saw the Primaris as yet another insult heaped upon the pile or at least a form of justification for those beliefs. The Imperium couldn't stand with the weaklings it already had so it needed to make new Astartes to challenge the might of the Legions.

In the individual battle? Sure it might wrong-foot the odd enemy commander but by the end of a given campaign, both sides are going to know that shock is gone regardless of who wins. The Imperium made a strong opening gambit but now everyone knows the score and they know how these new Astartes work, in some cases more literally than others.

A couple of the Alpha Legion novels do a pretty decent job of showcasing CSM interactions with primaris, actually.

In Sons of the Hydra(?), the main characters intercept some imperial coms and go, "Wtf is a primaris space marine?" Then they run into a couple guarding a tunnel and end up having a harder than expected time taking them out because they just don't succumb to the amount of damage the AL expected it would take. Which is a very fun interpretation of primaris from an era when the main difference between them and firstborn was an extra wound.

In Harrowmaster, we see newly-minted primaris chapter and some AL dealing with each other for the first time. The AL are able to deliver some sucker punches especially well at first because the primaris lack the first-hand experience with the AL that another chapter might have, and then they adapt and even start trying to use some trickery of their own to counter the AL. It's also noted that the super-competent naval commander of the AL is able to outperform the primaris despite their superior number of vessels because he finds that they behave very predictably. Later, the primaris are able to force the AL to adjust their plans during a naval battle because the primaris use a feint to disguise a more direct attack on the AL flagship.

So in other words, primaris seem to be a temporary, "Wtf?" moment for CSM who then quickly adapt. It's a big galaxy, and even long-lived individuals like some CSM probably haven't seen all the variety in the imperium's arsenal.

EDIT: And most factions who aren't CSM probably can't really tell much of a difference or don't care about the difference. Most eldar, despite being really old, haven't seen a space marine. So when some marines show up that are slightly taller than expected, it's probably more of a shoulder shrug than anything. If you're a necron lord that has had occassion to fight space marines before and now the metal boxes that float are slightly bigger and more numerous than before, you just shrug and go, "Oh hey, some of them figured out how to use metal spear tips instead of rock ones."

Tyranids don't generally seem to do a lot of reflecting on the implications of enemy technology or forms. On the macro level, the hivemind will just eventually register that more of the enemies are withstanding your venom longer and up the toxicity levels. On the micro level, maybe a lictor figures out he needs to aim for neck when he's stalking his prey.

I guess maybe tau would care as it would represent a notable shift in strategy/policy of their biggest enemy. But also, do tau even know enough about the imperium to be sure primaris weren't already a thing anyway?

Dok, no! you're gonna set the dumpster fire ablaze!!!

I won't talk about primaris because I don't like them, I skip.

But, I'll put in two cents about the shock of novelty.

I think there are really two degrees here: the first hand shock of veterans who get to see something new, firstly. I mean, as examplified by the CSM, when you've been doing that gak for long enough, I imagine you think that's ok, I can get this in hand... And then all your hard earned knowledge is made irrelevant by htat new tactic, by that new weapon, and you must start to learn all over again to survive... Awful. And those whose nerves won't take it because they can't get over it, or because they're new and no one told them about. They may be outright broken.

Then there's commanding echelons. Because this novelty must be accounted for. A way around must be devised, or a counter. Quicly at that. Time is of the essence because it sets you on your back foot. But, God knows, how long anything of this kind takes ages. Reports must be sent, summarised, read, accounted for, theorised, then all the way down to enforce and explain the new doctrine to thousands of soldiers. And then you must still check that said doctrine it the correct one and start all over again! Nightmare.

Innovation in a war truly tips the balance i believe, and indeed, its shock an awe are never overestimated.

And in an universe where said innavation litteraly can be some sort of silly magics, oh boy. However, if I may, and you said it yourself, there was always those races known for innovation and novelties (tau, nids...) while others stagnated. I personnaly liked it, it made them constrast in all this declining galaxy. But at the same time, I understand people who found it underwhelming because the sand box setting would never deliver innovations with true meaningful consequences as the universe was more or less frozen for you to play in. Maybe these people were really happy one inovelty actually hit and made things change.

I do agree it wouldn’t be permanent state of affairs. But even if it’s only a handful of initial encounters, or a single battle, it’s inevitably going to catch you out. And to quote Ciaphas Cain? It’s what you don’t know that gets you killed.

Alpha Legion I’ll accept would be good at such rapid adaptation, because that’s their jam. But “lesser” war bands? They simply may not survive the initial engagement, either at all or in anything resembling a cohesive force.

And so I think it’s an easily overlooked impact of the Primaris being sent out into the Galaxy. Spesh if they happened to be commanded by Guilliman himself.

 Mad Doc Grotsnik wrote:
To deliberately over egg this pudding? Consider Napoleon and his indisputable strategic nous, and introduce say, a couple of squads of SAS.

A couple of squads of the SAS would have done nothing for Napoleon, as he lacks the communication methods or logistics to support the kind of operations which the SAS are used for.

I was meaning as a foe, not a unit under his command. A deliberately exaggerated offering of how the unknown can wreck plans.

 Mad Doc Grotsnik wrote:
I was meaning as a foe, not a unit under his command. A deliberately exaggerated offering of how the unknown can wreck plans.

Still wouldn't accomplish much, for the exact same reasons. You already had Napoleon's forces facing the kind of activity that the SAS would be doing in the Peninsula campaign with the partisans. Adding a couple of better units would not have affected the campaign in any meaningful way. Time travel back 2 squads of the SAS with a mission loadout and they would be able to carry out a devastating ambush on a single column and then be combat ineffective as they have expended all of their ammunition and are not drilled in the operation of the weaponry of the time, nor are they familiar with the operational structure of the force they are working alongside, nor the transport and communication tools that a force like the SAS requires to operate. Take away the ability to rapidly insert to a target, hit it and then rapidly pull out via motorised transport and the SAS loses a lot of its operational usefulness. Plus the intel apparatus to support such operations would be completely lacking, hampering their ability to plan and execute the kinds of operations they would be trying to do.

Logistics and strategy wins wars. Doesn't matter how great your individual soldiers are, how much superior your equipment is, or how tactically brilliant your generals are, if you cannot keep those soldiers fed, keep that equipment supplied with ammunition, and get both to where they need to be, when they need to be there, and be able to replace any losses. The reason that special forces are so much more effective in the modern day is not due to the individuals themselves being superior in any way to their equivalents in the past, but due to the operational capabilities that exist in modern militaries to support the missions that special forces are used for, mainly in intelligence and communications thanks to inventions such as radio, aerial and satellite imaging etc.

If your thesis is "novelty translates to combat advantage" you couldn't have picked a worse faction to illustrate it working against than the guys who mutate and hang out in hell. Well, I guess you could have, you could have picked Tyranids.

The idea doesn't really hold up, though. Not any more than the idea that new shapes of warpspawn would somehow put loyalist marines on the wrong foot.

 Altruizine wrote:
If your thesis is "novelty translates to combat advantage" you couldn't have picked a worse faction to illustrate it working against than the guys who mutate and hang out in hell. Well, I guess you could have, you could have picked Tyranids.

The idea doesn't really hold up, though. Not any more than the idea that new shapes of warpspawn would somehow put loyalist marines on the wrong foot.

It would initially I think, but considering we're talking about centuries of combat experience you'll suppose they'd adapt quite quickly and it takes more than that to break them.

As for Chaos I think it's not the worst example if we look at those of the CSM who still have self preservation instincts and will maybe decide to leg it, or that doesn't have the means yet to face because it is a smaller warband.

Overall I think we're more about real breaktrhoughs, rather than variations or new mutation, if you know what I mean.

No, centuries to millennia old Veterans of the Long War are not going to be "offput" by some overgrown, VR trained, thin blood, Loyalist Scum. Please, try harder in your Primaris publicizing attempts.

 Mad Doc Grotsnik wrote:
But even if it’s only a handful of initial encounters, or a single battle, it’s inevitably going to catch you out.

But would it really? Would the German army have been caught by surprise and defeated because their US enemies had Garands in .308 instead of .30-06? Or would the difference have been too small to even notice unless some intelligence analyst took a very thorough look at some battlefield salvage? Would a Tau battlesuit pilot even notice a slight difference in shoulder pad shape before erasing a primaris marine from existence with a fusion blast?

Largely yes I think you're right MDG.

The galactic war of the 40k universe has been typified by stagnation, certainly from an Imperial standpoint. The rare innovators like the Tau have seen success in their little corner of the galaxy partly as a result of that. The fluidity of Chaos allows for almost limitless innovation and yet that is quite often prevented by the followers of Chaos who nominally still retain their Imperial doggedness and an inability to be truly pioneering. Quite a nice little irony in still being unable to remove those technological shackles that were bred into them.

The interesting thing about 40k is that every big player is ancient and at the end of their story. Their empires have grown long in the tooth and stick to their methods of war. Having one of these players suddenly burst back into a semblance of life does create a sudden terror. What else have they been hiding? An old enemy that you thought you knew and would do the same predictable actions ultimately deviating from those creates a problem. If you're also an old stagnating empire, alien or otherwise, how is your own adaptability? Of all the factions, the Imperials and the Orks are the least adaptable. But Orks don't really need to adapt because they'll take on any challenge with a laugh and with more dakka. Because Orks is da best.

The big terror of the Tyranids, despite them being gribbly is that they constantly adapt and evolve. It makes fighting them supremely difficult. They have a predictable goal in wanting the biggest lunch in the system, but how they seek it out can often prove unusual.

On the whole, we don't exactly like unpredictability in our society and yet too much of the same thing is overwhelming dull. A taste of something new keeps things ticking over.

Granted, the schock of novelty is not automatic in a galaxy as large and diverse as 40k.

But it can be. Especially when we're talking breakthroughs.

And not only primaris, it's a starting point for the thread but the discussion doesn't need to stick to them in particular.

 ThePaintingOwl wrote:

 Mad Doc Grotsnik wrote:
But even if it’s only a handful of initial encounters, or a single battle, it’s inevitably going to catch you out.

But would it really? Would the German army have been caught by surprise and defeated because their US enemies had Garands in .308 instead of .30-06? Or would the difference have been too small to even notice unless some intelligence analyst took a very thorough look at some battlefield salvage? Would a Tau battlesuit pilot even notice a slight difference in shoulder pad shape before erasing a primaris marine from existence with a fusion blast?

I’m not familiar with rifles and that from a real world perspective, so I’m afraid I can’t really answer your exact poser properly. Did one have a noticeably longer range, or was generally more accurate, had a large clip (magazine?) because those things do matter.


But consider other innovations, such as Radar. A secret British invention which allowed us to win the Battle of Britain, as it meant we could detect incoming waves and scramble fighters “right place, right time”, ideally before the bombers got anywhere really useful, and just as their own fighter escort were approaching the Point of No Return.

See the successes of the early SAS in the African theatre, where relative handfuls of total nutters punched far above their weight. Or the stage magician’s tricks in that same theatre (such as turning spotlights into something approximating a strobe, so enemy pilots couldn’t adapt their eyesight).

All non-traditional, all innovations.

The Primaris Innovation is of course something quite different. But their base weapons have a longer operational range. Their armoured columns are now anti-grav, opening up avenues of attack nobody has seen from The Imperium in….ever. Even sillier stuff like jump pack auto cannon carriers are entirely new, having no Heresy equivalent I can immediately think of.

Will a Fusion Blaster still reduce one to a greasy smoke? Yup. They’re tougher, but not that much tougher. But their new toys still allow new tactics and strategies. The longer range of Bolt Rifles alone is a significant change, as you’re likely to find that out the hard “you may not survive this” way. And depending on the situation, such surprises absolutely can make the difference in outcome. And hey. Putting the Fusion Blaster to one side? They just got far more resilient to anything smaller. Which again is a significant shift in how you need to go about successfully engaging them. If you’ve done your force calculations and sent in a force capable of dealing with a Space Marine Demi-Company? Yeah that’s not enough force now. Like. At all. They can engage you at longer ranges, and (worst bolter prawn aside) even more difficult to put down permanently.

It’s shifted the calculation of attrition. Yes you still have the ability to carry the day. But the job just got an awful lot harder.

@Mad Doc Grotsnik: You ever watched the movie "Soldier"? (If you haven't, I highly recommend it). Well that's how I envision Primaris vs CSM. Basically, Primaris are better physically, but the extreme experience of your average VotLW wins the day.

The wisdom of Kurt Russell shows us the way.

Yeah I can accept that. Certainly I fully accept experience counts for a lot.

But I think folk may be underestimating just how predictable Imperial Forces were prior to the Primaris Crusade.

Certainly in initial encounters, the novelty and sheer unknown of the Primaris and their weapons would’ve added to their overall impact.

Their tactics may be somewhat unrefined, and easy enough to riddle out after the fact. But that initial “wtf” is still a window for your plan to go hideously belly up.

Definitely look at how Primaris are equipped and armed. Even going back to the Heresy? There isn’t always a direct comparison. Fielded as a single force, that’s rather a lot of surprises in a short time, from a foe you really wouldn’t think capable of such surprises.

And remember, my poser here isn’t “therefore Primaris am the invinciballs”. Just that their nature as New would’ve been part of their initial successes.

Right, but the problem is that didn't last very long.

And I'm going to argue that the initial success of the Indomitus Crusade wasn't down to the Primaris being new but the fact that Astartes Chapters, Militarum Regiments, Navy Squadrons, Custodes, Mechanicus Conclaves, Knight Lances, Sororitas Convents, and Titan Legions were all working in cohesion with Guilliman at the helm.

I'd also argue that the presence of the Custodes was a bigger "Oh gak" moment than anything the Primaris threw out, especially for the Traitor Legions who know the pedigree of these warriors from the Heresy.

Depends how cross-communicative Chaos forces are.

A smaller warband might be entirely wiped out, allowing that initial surprise to kick in again on the next engagement. And even where there are survivors, it’ll depend if there’s any cross-warband communication, and indeed anyone actually willing to listen and not simply shoot the messenger.

Now that is gonna vary wildly, because of course it is. Whether you knowingly or not have Alpha Legion assets in your force, then word is almost certainly going to get out. That’s what the Alpha Legion do. But, if it’s a Khornate Warband being stomped? The chances seem less so.

It’s absolutely not a secret you can keep indefinitely, but as the Primaris themselves gain actual combat experience, the novelty wearing off may well be suitably mitigated by the Primaris knowing what they’re doing.

Traditional comms aren't the only method of communication though, especially amongst the forces of Chaos.

Word spreads fast when the Warp itself whispers with the return of the Avenging Son.

These counterpoints are not out of place, so again, we can agree that while this is not false, we should minor it's effect in 40k's setting. And it is mostly faction based in scope and magnitude, even if examples of it exists throughout the lore for most factions.

The CSM in particular do indeed count on their experience to overcome or adapt but should a real breakthrough occur, it would seem logical that again, the response and management of first encounter awe would greatly vary.

Regarding the garand, really, from the victim's perspective, that doesn't change much. The deal with the garand was that it was the first rifle to massively equip and army while being semi auto. The cartridge itself makes little difference in that case. Calibers debate are a whole other kind of debate and there is much, much to say about this topic!

Is there though?

We've kind of gone over this about four times where one side says that there's a surge of shock at the Primaris while the other argues that there isn't really.

It goes back to individual engagements which in turn are discounted to the wider galactic battleground.
Yeah, a newly minted Renegade Chapter might get bodied but even then it's not like they wouldn't immediately adapt to a new foe because they're still Astartes.

Again though, I'd make the argument that the Primaris were a tiny part of the wider whole which is for a fraction of time, the vast armies of the Imperium were wielded by a single hand. A hand that excelled at the strategic level and had an understanding of logistics beyond any other Imperial Commander.
Guilliman is the shock and awe, not the new type of Space Marine.

It’s not just Primaris being bigger and tougher though.

Eliminators, Inceptors and Suppresors in particular have no particularly direct equivalent in the history of Imperial Forces.

Hellblasters and Eradicators, in terms of being uniformly equipped with Special Weapons haven’t been seen since the Heresy era.

The first three are of particular importance to here. Eliminators are heavier hitting Snipers, more about outright killing/maiming than disruption. The jump pack units aren’t HTH oriented, and pack considerable ranged punch. You might see the Inceptors in silhouette and assume a Demi-assault squad, only to be on the receiving end of high calibre bolt weapons, or worse, a deluge of plasma bolts.

The sheer newness of those amongst the Space Marines isn’t something you’d initially expect. A Veteran of the Long War, who hasn’t gone insane, will of course adapt. In time. But even if it’s only a couple of minutes, or a few seconds, of frantic vox discussion, getting a counter tactic going isn’t instantaneous, and that can cost you a battle.

But not all Chaos Marines are that experienced, let alone anything remotely approaching sane.

Consider that Chaos is by definition Not A Cohesive Force. You might’ve planned on the frothing maniacs over there to be let off the leash to cause havoc, havoc you can exploit. But if they run up against a squad of Hellblasters? There’s some chance that they’re just gonna get annihilated before they cause much, possibly any, mess.

Such a scenario drastically alters the flow of the battle. If your distraction has been stomped on hard, that’s an asset you’ve lost, potentially for little to no gain. It doesn’t mean “therefore you lose the battle”. That’s not what I’m arguing. But it is an impact, and makes things dicier.

And such a single “oh well that went unexpectedly wrong” can turn a wider campaign, as all your predictions and Plan B’s etc likely won’t have accounted for this new foe’s new toys. And again, in the time it takes you to counter that advantage, your foe may well be pressing their advantage.

And Guilliman over anyone would’ve taken that into account. Now whether that means he relied on Shock and Awe, or was able to commit unexpectedly smaller forces to secure certain areas, who knows. Almost certainly both I’d reckon.

 Gert wrote:


Again though, I'd make the argument that the Primaris were a tiny part of the wider whole which is for a fraction of time, the vast armies of the Imperium were wielded by a single hand. A hand that excelled at the strategic level and had an understanding of logistics beyond any other Imperial Commander.
Guilliman is the shock and awe, not the new type of Space Marine.

I agree with that statement.

I think you're focusing on two very specific things to make your points Doc.

First is the idea that the various factions and races only ever come up against Astartes and not say Necrons or Tyranids. The idea that the idea of a dedicated sniper unit (which already exists in the form of Scouts) would cause disruption beyond the norm for enemy combatants when things like Deathmarks (which literally phase in and out of reality) or T'au Sniper Drones (which have far greater maneuverability) exist is a bit weak.
Likewise, the concept of aerial troops with heavy firepower is not a new one seeing as the T'au pretty much made this a major part of their warfare with the various patterns of Battlesuit and Biomorphs like the Shrike are present among Tyranid Tendrils.

Secondly, you're focusing way too much on Chaos forces and IMO inaccurately portraying them when you do so.
There are absolutely those among the forces of Chaos that are certifiably insane but they are not the norm nor does that make them incapable of strategy. In terms of theatre combat, and not as a societal threat, Chaos would not nearly be as much of a threat if those who led the majority of warbands, fleets, and Chapters were not capable individuals.
Many Chaos Lords will have been high-ranking members of their Legions during the Heresy or officers from their Chapters before turning renegade with hundreds if not thousands of years of practical combat experience under their belts.
These are also going to be warriors who have survived the absolute worst plane of existence imaginable, living in a state of constant warfare and survival compared to their Imperial counterparts who often have rotational duties. There is no rest for a Chaos warband when every corner hides a new foe and even basic supplies can be difficult to come by.

I'm not disagreeing with the notion that there was some value from the Primaris reinforcements but it is my opinion that the value came not from shock at new types of soldier or weapon but that the Imperium was able to rally so efficiently (at least for a time) and had one of the greatest tacticians in Imperial history at the helm to utilise the new assets in the best way possible.

Kind of, I guess. I think (and I appreciate this might feel like a back pedal cop out, and so be it) I didn’t really explain myself that well in the OP.

But it was specifically in pushing back against Chaos forces, as that’s who and what the Indomitus Crusade primarily targeted, and were at that time the Most Present Threat with the great rift opening.

Chaos forces really aren’t all that cohesive though. Time and time again we see loose alliances agree on a common target or objective, and still be backstabbing and “my real plan is” all the time.

Let’s say you’re a Thousand Son’s Cabal. Whilst your erstwhile allies of the moment are off doing something, you’re getting underway with a ritual or summoning or something. Those take time, and that required time is all factored, likely with some contingency. But when your erstwhile allies of the moment are caught up by this new and “hold on, give me a moment” type threat from such an unexpected quarter? That may blow it all for you, just as a sneaky attack by Sisters of Silence would too.


Automatically Appended Next Post:
Thought to briefly cover how other races might cope?

Craftworlders - It’s foreseen and so largely accounted for.

Orks - Dese Beakies is even ‘arder. WAHEY!!!!!!

Tau - Don’t worry Lads, I’ve got an idea.

Necrons - “Meh”

Tyranids - What is that intriguing new spice! We must add it to our own recipes!

Dark Eldar - they’re a bit tougher to capture, but man they last a lot longer under our tender ministrations, we’ll take a dozen. Chapters.

But that's not Chaos being incohesive that's battle tactics.
If a commander needs time to do a specific thing (ritual, data download) then they're already on the back foot unless they've put themselves in an extremely strong position in the first place. New types of soldiers and weapons aren't going to make that commander's mission any more difficult than it realistically already was.

But on the point of Chaos being incohesive, so is the Imperium. How many commanders are out for personal glory or commit to an engagement because "The God Emperor sent me a vision"?
The same criticisms leveled at the forces of Chaos are equally applicable to almost every single other faction in the game besides maybe the T'au and Tyranids.
This again goes back to my primary point about the leader behind the Indomitus Crusade being the real "shock and awe" and not the Primaris themselves.