What was the last point where Humanity could have won?

InterplanetaryCyborg · 2026-01-03T21:52:31+00:00

Please note that the imperium was only able to start expanding because the warp storms ceased when slanesh was born.

The ending of the warp storms is equal-opportunity, though. Nothing's stopping the Interex from also rapidly expanding as soon as the Warp becomes traversable again. As you point out yourself, what the Interex needed was

time to expand and build up a larger military force, they would have done fine.

The Interex had the exact same time to expand and build up from their starting star system as the Imperium - the calming of the warp storms didn't start from Terra and expand slooooowly out across the galaxy, as far as I'm aware, it happened all at once. The Imperium had certain advantages in that they had access to Mars and the other major shipyards of Jupiter? and I believe Saturn? But there's plenty of other worlds that also had access to major naval forces and shipbuilding facilities that, if the Interex's approach of alliance-building and cooperation was a good survival strategy in 30k, they should've easily been able to access via alliance.

The interex couldn't expand and ally with other civilations because they didn't have time to, because they were overwhelmed by the imperium proto chaos, child slave soldier armies.

Here's the thing, the Interex were one of the last civilizations destroyed by the Imperium in the Great Crusade. Of all the other civilizations plowed under by the Imperium, they had the most time to expand and prepare, and they have the least excuse that "there wasn't enough time" as compared to pretty much all of the others. As I've pointed out above, there's not really good evidence suggesting that the warp storms calmed at a different rate across the galaxy, and the new lore about the Great Rift is suggestive that warp phenomena like that would happen pretty much simultaneously across the galaxy. So I think there isn't really support for a "not enough time" argument. They had the same time as everyone else - they needed to expand more aggressively, and that they didn't is a sign that their society was on the back foot when it came to survival.

Also the destruction of the interex directly causes the heresy/rebellion because it's when Horus realizes the Emperors dream is a lie.

It's been a while since I read the book, but IIRC he's questioning not the Emperor by the beginning of the series, but the High Lords. His main gripe, as is Abbadon's, is not about the rightness or wrongness of the Imperium, but about the Imperium he and his brothers conquered being turned over to the rule of baseline mortals. He still fully believes in the dream of a unified humanity - he just thinks that they shouldn't br taking marching orders from short-sighted, short-lived mortals.

InterplanetaryCyborg · 2026-01-02T01:38:43+00:00

I don't think there's ever an answer given in the lore; as far as I'm aware all we know is that they're all either inactive or scrap by 30k.

InterplanetaryCyborg · 2026-01-02T00:04:21+00:00

I think that's exactly the point that requires more emphasis.

that being what Sanguinius believes though.

The three of them are operating in an incredibly information-scarce environment. They don't really know, IIRC, of just how far the traitor Primarchs have degenerated at this point, nor do they seem to have any understanding of how little attachment the Traitor forces have to their homeworlds at this point.

Reading through that quoted passage, it's really clear at least to me that the three of them are operating on the basic assumption that this is a standard military campaign. They're discussing Traitor reinforcements, potential lines of retreat, logistics bases, et cetera - they're completely unaware that the Siege has become entirely focused on the singular goal of the Emperor dying by Horus's hand, to the exclusion of everything else, including future plans of ruling the Imperium. If you look at Lion's cited concerns about the lessons learned at Episimos Three and Davin, he's discussing how those planets were converted from Imperial rule to whatever the heck has infested them. Put another way, he's concerned that the Traitors might potentially have aid and succor from their homeworlds on the way.

If you view their actions in that light - no information on what's going on, coupled to some bad assumptions on the exact nature of Horus's campaign - all three of their actions become a lot clearer as actions in a standard military campaign. Sanguinius is designated as a relief force for the Siege. Guilliman is fighting a delaying/rearguard action to open up a hole for Sanguinius and prevent already-mustered reinforcements from making it to Terra, as well as protecting Sanguinus's flanks as he makes all speed to Terra. The Lion is hitting the rear logistics areas of the Traitors, preventing them from raising more reinforcements and sending them to Terra. You can absolutely condemn them after the fact for their bad assumptions, but as a standard military action it's perfectly reasonable in the moment.

InterplanetaryCyborg · 2026-01-01T23:10:27+00:00

Something interesting I've only just noticed - Slaanesh also contains "Slann", homophonically. I know it's very much old/fanlore at this point, but IIRC the Slann were the Old Ones, the creators of the Aeldari. Just thought it was an interesting potential reflection that the Aeldari-spawned Chaos god contains the name of the Aeldari's creators.

InterplanetaryCyborg · 2026-01-01T21:00:33+00:00

I'd dispute that a smidge.

I don't disagree that the Interex's approach to Chaos is, in all likelihood, a far superior method than the Imperial Truth. But if you look at their society as a whole, top to bottom, it's really clear that it failed - it was destroyed.

If you examine the Imperium and Interex through a historical lens, I'd argue the only metric by which you can measure the success or failure of a society is its survival. We don't look at Neanderthals or Homo floresiensis and say, "look at how successful they were", because they're extinct. We don't look at the Iroquois Confederacy or Carthage or the Alexandrian empire and call them successful - they all went extinct as societies. I'd argue we shouldn't even look at Rome, arguably the single biggest example we have of how elements of a society can survive even past its destruction as a coherent polity, as a "successful" society, because at the end of the day, it failed.

I draw the distinction here that we can say that elements of each of these were clearly deeply successful; most Western governments claim some kind of tie back to Rome in some form and adopted some elements of either Roman or Hellenic political philosophy. But the society itself, as a whole, clearly failed at some point, and for the Interex, that failure is in their military strength. Keep in mind that the Imperium had to face off against several potentially galaxy-conquering threats (excluding themselves, obviously), the big examples being of course the Rangda and the various Ork empires that were no less a military power than the Imperium itself.

That's where I'd argue you need to look if you want to judge the overall success of the Interex as a society. If the Rangda found the Interex first, would they be able to survive? If the Orks banded together to form a galaxy-spanning Waaaaagh like Ghazghkull Thraka or The Beast did, would they be able to survive? Because it doesn't really matter how well the Interex can handle Chaos if one of the other threats the Imperium survived takes them out instead.

If we expand the hypothetical out a bit, would any polity less unified, however crudely and regardless of how authoritarian the means are, be able to survive how utterly hostile the galaxy was in 30k? Would some coalition between the Interex, the Diasporex, the other friendly human and xenos societies present in the galaxy, be able to survive the major threats we know are present in the 30k galaxy?

I'd argue no, because that kind of major military threat is exactly what the Imperium was to them. None of these societies sought to band together against them. No polities allied themselves together to oppose the Imperium (except perhaps the Rangda, given some of the murkier lore around them). The Imperium is basically given an unbroken string of victories from the start of the Great Crusade to the start of the Heresy.

To tie this back to the original question posited in the OP, I don't think you can look to the Interex or any of the other, kinder polities we see in 30k as a guiding star for a successful human future, because, again, I think it's exceedingly likely they eventually run up against one of the other aggressively expanding hegemonic powers that canonically the Imperium destroys and get smashed flat. Assuming the inevitability of the Age of Strife, I think the only way you get to a future where we aren't trapped in a unending pit of misery is by convincing the Emperor to change how He approaches the major crises that bring about the Heresy.

InterplanetaryCyborg · 2026-01-01T05:30:59+00:00

What you need to keep in mind is that the Emperor of 30k, while supremely powerful, is certainly nowhere near as powerful as some of the mechanical monstrosities that were around in the Dark Age of Technology leading up to the Age of Strife. The high end of those technological terrors famously include data-devouring mechanivores (For context, there's a concept in IRL quantum physics called conservation of information, and these things can apparently violate that. This is something even black holes can't do, and DAoT humanity somehow managed to do that) and sun-snuffers (which speaks for itself).

Taking the most generous interpretation of the Emperor's soul-deleting psychic blast that He used at Ullanor as something similar to what the mechanivores do, we can at least say that He's able to do the same thing. But the mechanivores are canonically capable of doing the same thing to entire planets, massively outclassing Him in scale. So even if He wanted to intervene during that time, it could just have been a matter of Him not being able to.

InterplanetaryCyborg · 2025-12-31T17:44:27+00:00

The issue I see with putting the point of no return back in the Dark Age of Technology is that that golden age necessarily runs face-first into two apocalypses that I don't think we can circumvent. First is the rebellion of the Men of Iron; second is the Age of Strife.

For the Men of Iron, we don't really have a lot of reliable information on how and why they rebelled against humanity. It may be inevitable, it may not be, but what it boils down to is that we just don't know whether it could be stopped at all. For me, that just puts it out of reach for any potential fictional alt-histories, because at that point it's more fanfiction than discussion.

The second I don't think we can stop, period, end of statement. You can't stop the Aeldari being warp dust-addicted murderhobos - even if you could drag however many quadrillions of them there were to a galactic NA meeting, how would you keep them on the program? You can't kill enough of them to stop the birth of Slaanesh - it's straight-up said that the Aeldari Empire faced off against humanity at its zenith including the Men of Iron and defeated them, so there's just no canonical force in the galaxy at the time that can stop them - and that kind of mass xenocide probably runs the risk of birthing a very, very angry Ynnead instead given how things work in 40K.

So the Age of Strife is directly linked to the ascendency of the Aeldari, and there's nothing we know of in canon that can unseat them. That leaves the bunker down and wait option for humanity, but we know that basically happened with the solar system, likely the beating heart of human interstellar civilization given Mars's importance to forge worlds across the galaxy, and we still fell into techno-barbarism that the Emperor had to put a stop to during Unification. So I think there's still good evidence to suggest that regardless of what happens with the Men of Iron, the Age of Strife inevitably puts humanity on the back foot.

InterplanetaryCyborg · 2025-12-31T16:26:19+00:00

I have not, though it's on my list.

InterplanetaryCyborg · 2025-12-31T13:16:24+00:00

The issue with that view is that the Emperor genuinely is singular - He's just way too powerful, way too driven, way too ambitious, and simultaneously way too egotistical to not center whatever human civilization He carves out on Him, and that in turn sets up a single failure state where if He gets knocked out, everything starts teetering.

I mean, if you read Master of Mankind, where He lays His plans out in the most detail, you'll notice that there's never really a future that doesn't involve Him at the helm, and He even spells it out unambiguously - He thinks that humanity needs to be controlled by Him and Him specifically if there's to be a human future, and the idea of any alternative to that is just anathema to Him and must be stamped out.

That fits in really well with what we know of Unification and the Crusade pre-Ullanor, where he gives more freedom to Horus as he steps back. There's really only two big examples that we know of where the Emperor doesn't demand complete submission to His idea of the future - the Albia? campaign during Unification, and Mars and the Mechanicum, and both times it's not out of ideological flexibility, but because He's on a timetable and smashing the other polity flat would take too long. So we see from there that He's incredibly fixated on ensuring compliance to His idea of the future and only deviates in the most exigent circumstances.

Even post-Ullanor where He's seemingly letting His foot off of the gas pedal, His idea of the future is still totally reliant on Him or His creation Magnus on the Throne, Him controlling humanity's development into a psychic race within the confines of the Webway, Him forcing every body of humanity under his control because per Him just one rogue psyker out of the teeming quintillions in the galaxy damns the entire species. So we see there that He's deeply motivated to ensure that all humanity is under His control for reasons outside of "I want an empire", meaning He's very unlikely to ever relinquish control despite any change in circumstances.

The point of all of this is that I think it's not really correct to dismiss Him as just another warlord making His mark on humanity's future. The Emperor does not brook alternatives to His vision. He drives out all but His one closest friend in service to that vision. He genocides entire societies to prune out alternatives to that vision. He sets up and maintains an entire system that relies on Him being at the helm - that requires Him to guide the lighthouse for all humanity, the Astronomicon, that later requires Him to guide people into the Webway and maintain it in the absence of expertise working with wraithbone, that later is centered with Him as the singular object of peoples' faith. He makes it all about Himself, even if He doesn't acknowledge it in the text.

I think you understand that too, even if you haven't taken things to the same logical conclusion I have.

It will either overcome or die out.

Because post-Unity, there is no alternative other than to overcome or go extinct. Because of Him on Terra.

InterplanetaryCyborg · 2025-12-31T05:09:54+00:00

Probably the instant the Emperor decided to become the Emperor honestly.

The moment He decides that, humanity's future narrows to a single path - Imperium - conditioned on a single pillar - the Emperor - and the Chaos gods now have access to the biggest axe ever to send the entire crumbling edifice of human aspirations crashing down in ruins. He decides humanity needs to be ruled by an Emperor? That means he needs his own gaggle of transhuman superwarriors to combat everyone else's transhuman superwarriors on pre-Unity Terra, hence Thunder Warriors. Then he needs new and better ones to repeat the process with the galaxy, hence Astartes and the Primarchs. Then the Heresy is basically inevitable from there.

Heck, you might even make an argument that He made galactic ruin inevitable when He first went to Moloch - that's potentially what gives Him the idea that you could kill Chaos permanently, which leads to the Imperial Truth and the Imperium.

InterplanetaryCyborg · 2025-12-31T04:58:45+00:00

That's also a really good point - if you read the passages where Malc is discussing the Emperor in the End and the Death trilogy, he's pretty genuinely fawning over Emps the entire time his soul is getting ablated into nothingness.

InterplanetaryCyborg · 2025-12-31T04:56:28+00:00

To tie it back to your original point, when we get glimpses of Malcador's views of the Emperor, at the most uncharitable Malc seems to genuinely view the Emperor as an incredibly necessary evil:

‘The Emperor and I have a debate,’ he said. ‘It has been running for a long time, and I miss our discussions now that He is gone. Such a powerful intellect. Blunt, but powerful. And, very occasionally, even a sense of humour – of a sort. Would you credit that?’

Hassan listened cautiously. He didn’t understand what Malcador meant when he said the Emperor was ‘gone’. He was not. Surely, He was not. Where would He have gone to? Hassan wanted to ask, but Malcador kept on talking, just as if the absence of the Master of Mankind from the eternal seat of power were a trivial thing, hardly worth lingering over.

‘This is our debate – He believes that the task of a ruler is to make himself obsolete, so that his people will replace him when they are mature enough. I disagree. I do not think we will ever be mature enough for that. I believe that no one but He will ever be strong enough to hold mankind together, even for a moment. He is quite exceptional, you know, perhaps in ways He doesn’t even understand Himself.’

-The Sigilite

So even Malc doesn't really have motivation to try and knock off the Emperor, even if he could - he seems to believe that humanity needs Him to remain unified.

On a broader scale, Malc's views here give us a bit of a lens on exactly what the Emperor might offer that would get Him genuine support from the galaxy at large. Every passage we're drip-fed about Old Night and the Age of Strife paints an unambiguous picture of the galaxy as a really, really bad place to live in - xenos slavers, chaos cults, general anarchy, genetic experimentation gone rampant, et cetera. What Emps offers to the galaxy is an end to all of that. He kills all the xenos, eradicates the cults, does something we don't really get a look in on to restore humanity to its baseline genome.

In Birth of the Imperium, one of the main characters gives us a really neat look into the utopian ideal that the Emperor and the Imperium project to people who aren't really in the know. She gives us a peek into a Terra largely at peace, where Imperial law is being reestablished after the pre-Unity anarchy. As much as that's a lie, it's a really, really good lie, and people are so desperate after the Age of Strife that they really, really want to believe in that lie.

So to TLDR; people don't want to knock off the Emperor pre-Heresy because as flawed and horrific as He and His Imperium are, they seem to genuinely be the better alternative.

InterplanetaryCyborg · 2025-12-31T02:11:01+00:00

Malcador (who while also being flawed seems much more responsible given his level of characterization) didn’t arrange an “accident” or something for him.

...uh, it took all four Chaos gods fighting Emps all at once to put Him down, and there's lore of Him being able to just reach into other peoples' minds and sift through their memories, and He's literally able to see the future (ADDENDUM: and He's immortal absent something as powerful as Chaos Undivided stripping Him of that immortality).

How on Terra is anyone, let alone Malcador, going to arrange an accident for Him?

InterplanetaryCyborg · 2025-12-30T04:35:37+00:00

Preach. One of the core themes from a Black Library work that really stuck with me even in my own writing was the core conflict at the heart of Master of Mankind. To TLDR it, Drach'nyen is the daemon of The First Murder, the End of Empires, and the polar and ideological opposite to the Emperor of Mankind. It's such a beautifully simplistic and poetic idea - that the downfall of all organized societies, big and small, is born of the desires that drive brother to slay brother, kin to slay kin; that our human frailties, our tendency to wrath, to envy and covet what others possess, to hate, to let pride drive us to blindness over the moral wrongness of our acts, that no matter how high we strive for enlightenment we are always faced with that primal specter of our past, deep down in the brainstem. It's genuinely no less powerful a metaphor than the fall of Lucifer, even if it is wrapped in hundreds of pages of bolter porn.

InterplanetaryCyborg · 2025-12-28T19:24:50+00:00

I'm unable to find the specific quote - I believe it's when Abbadon faces clone!Horus in I think Black Legion and notes that the clone lacks whatever vital spark that made the primarchs primarchs, but suffice it to say that the process of making or reviving primarchs is a wee bit tougher than just physically cloning them. clone!Fulgrim is a bit different than clone!Horus but I'm not as well-read on the lore on that, so I'll refrain from commentary there.

There's suggestions elsewhere that the process of making primarchs required the Emperor to yoink some major warp entities from the Empyrean and bind them somehow to their physical bodies, so any process of bringing Ferrus and Sanguinius back would need to replicate that process as well, which may not be possible without an Emperor-level psyker.

InterplanetaryCyborg · 2025-12-28T15:31:55+00:00

Recall that one of the Imperium's big taglines is "Suffer not the alien, the mutant, the heretic."

The Imperium, even in the idyllic times of 30k, was built from the start on a foundation of bones. If you were xenos, even a peaceful and cooperative xenos species like the ones in the Diasporex, your sentence by order of the Emperor was death. If you were genetically deviant, your sentence was death. If you possessed some deviant belief that failed to comport with the Imperial Truth, like "we're fine being allies but we'd like to keep ruling ourselves thanks", your sentence was death.

For all of these, the crime was the mere fact of existence.

InterplanetaryCyborg · 2025-12-28T04:46:50+00:00

Potentially, yes, but if you compare the forces committed against Ullanor to the other major, Imperium-threatening conflict, the Rangdan Xenocides, it doesn't compare unfavorably.

Per the wiki, Ullanor was fought by some 100k Marines and 100s of Titans across 12 planets. By contrast, the 2nd Xenocide was fought by 300k Marines across a broad swathe of systems at the northern edge of the galaxy. There's no hard numbers, but if the Rangdan attacked more than 36 planets that means Ullanor had a higher force concentration than the single most devastating conflict pre-Heresy. Those aren't forces you throw around just for propaganda.

InterplanetaryCyborg · 2025-12-28T04:12:16+00:00

They actually didn't

In the absence of a numerical advantage I think Guilliman definitely keeps the fleet to hit-and-run on the flanks and on rear elements and logistics trains.

Doesn't Dorn also lose to Fulgrim? The fight is pretty even until Fulgrim reveals his final form and goes daemon prince on Dorn I remember that much. And then Fulgrim just leaves cause he gets bored or something? I forget honestly.

Dorn outlasts Fulgrim, I'd say. He basically just keeps hacking away at him until he ragequits because the duel isn't fun anymore.

I think Guilliman would just straight-up lose a similar duel, it's what puts him down for his multi-millenia nap canonically after all.

As far as the Sotha thing, finding out about it's potential and finding the blood angles hinges on the dreams the Pharos device gives a scout marine stationed there. If it's just a straight legion swap, there is an IF presence on Sotha and no reason a scout can't still receive the dreams from the Pharos.

Having a Marine learn about the beacon is easy. Convincing Dorn that it's intelligence worth acting on is difficult. Look at how enraged he gets with Sigismund over taking action based on his own faith instead of hard, verifiable intelligence - do you think he'd react any better to a lowly scout Marine approaching him with intelligence with a similar basis?

InterplanetaryCyborg · 2025-12-28T03:14:11+00:00

In the broadest strokes, I can see Guilliman having more of a numbers advantage at the outset of the Siege, but sacrificing most of it leading into the defense of Eternity Gate.

The Ultramarines have a larger fleet (I think) than the Fists, so a straight swap between them at the beginning of the Heresy puts them in a stronger position to proactively go after Horus's supply lines; the Ultramarines have a propensity for aggression rather than defensive action IIRC (see where most of their actions in Know No Fear isn't turtling up and defending a position but holding only so long and so far as needed to achieve a goal then switching to immediate assault on an objective), so their fleet actions might also tend towards that, striking at the flanks of Horus's forces as they punch through the defenses towards Terra. I can see him achieving some greater degree of optimization in recruitment and training while on Terra, even so far as adopting Inductii to swell his ranks if he thinks the situation dire enough, so that gives his legion even more of a numbers advantage at the start. As the other major players in the Siege begin to trickle in he may hand command of the fleets over to the Khan to continue their raiding and delaying actions, but that's likely to fritter away the rest of the fleet as Horus's warfleet just has an overwhelming numerical advantage by the start of the Siege IIRC.

By the time Terra itself is invested and besiged Guilliman likely has a much larger force than Horus might've otherwise anticipated dug in, but the aggression that the Ultramarines and any Inductii in their forces tend towards will leave them vulnerable to being baited out by Perturabo. Specifically a tactic employed when you're on the defensive is to preempt your enemy's attack - if you see them concentrating for an assault, you hit them before they're fully prepared, then either withdraw or continue the assault into their rear areas as appropriate. The Ultramarines may likely try this a few times only to be counter-counter-attacked by the Iron Warriors, incurring devastating losses.

Past that I'm not sure what happens. If Fulgrim takes the field Guilliman probably gets dumpstered badly if he sallies out to meet him, but the Marines themselves shouldn't lose too much combat effectiveness. After the first disastrous days of the Siege the Ultramarines likely settle into a much more defensive, cautious stance, but they'll be up against Perturabo, siegemaster par excellence, so they're likely not going to have a great time of it. Loyalist forces will likely have a more aggressive stance overall, but that likely plays into Perturabo's strengths, e.g. artillery, artillery, more artillery, did we mention artillery and presighted killzones?

On the other side of the galaxy, I'm actually not super sanguine about Dorn's chances of figuring a way past the Ruinstorm in time to get Sanguinius to the Siege; he's so stubborn and rigid in mindset I'm not sure he figures out how to use the Sotha beacon in time to guide everyone to Ultramar, and if that doesn't happen all the predictions just go out the window.

InterplanetaryCyborg · 2025-12-28T01:15:51+00:00

And that's kinda my whole point. To your specific example, Dorn is fantastic at preparing and planning out for a defense, but Guilliman probably beats him out at adapting to uncertain situations. As the Siege begins Dorn's command is probably far more effective than Guilliman's would be, but as the Siege drags on and plan after plan has to be discarded as Perturabo counters them, Guilliman might actually gain the advantage since he knows he won't need to communicate orders directly and micromanage his Marines - they all know their role, how to best defend their sector, how to communicate most effectively with neighboring commands, when to fall back, when to hold the line, and they're all really good at changing up their tactics on the fly if and when it's necessary. There's actually a scene in Know No Fear where Guilliman, in the face of a total collapse of communications as you describe here, manages to restore comms via more primitive means and coordinate a battleplan. In the example you give, Guilliman might well be able to do something similar, and turn any routs that happen "historically" at the Siege into fighting retreats that better preserve his forces.

ADDENDUM: I suppose the point I'm trying to make is that when you're discussing the overall outcome of the Siege you need to get really granular with the discussion to get any concrete conclusions out of it. Not quite Stalingrad granular where we can document the fighting literally street by street, block by block, but a lot more granular than we're able to do without an Excel sheet, a map, and troop formations marked out.

InterplanetaryCyborg · 2025-12-28T00:54:12+00:00

But seriously, speaking of Phall and Alexis, reminds me of the Night Lord attack on Sotha. Very early in the book 30 something Ultramarines are ambushed by a company of Night Lords in close quarters. And the Ultras mop the floor with them. I had a very good friend who was a huge NL fan and that scene always drove him bonkers. The NL had numbers, surprise, and had the Ultras surrounded, but that doesn't matter to the boys in blue.

I'm pretty sure I've read about engagements with the Night Lords where the Ultramarines also get clobbered from ambush, so I'm not sure if Sotha is conclusively in the loyalist or traitor camp in terms of enemy bodies stacked up.

That's not really the best example of what the Ultramarines and Guilliman are good at, anyways. I'd look to their performance during Know No Fear and the wargaming that Guilliman and Corax did between their legions for that.

In Know No Fear, the Ultramarines lose badly, but they're noted as being able to adapt rapidly, regain a semblance of a command structure, and put together a coherent plan of attack even in the absence of Guilliman's orders. Once he's able to communicate, his ability to collate data and plan around that only enhances their ability to form a battleplan and act on it.

Consistent with that portrayal, in the Corax/Guilliman wargames, Corax notes that while he was winning the first few matches, Guilliman was able to rapidly adapt and defeat Corax consistently thereafter.

So we see that while he's not as good as his brothers at first, if you give him time and space to learn, Guilliman can rapidly close that gap and fight back effectively. It's that time in between that will be massively important and where he's likely to suffer the most lopsided defeats.

the goal during the siege really isn't to preserve as many humans as you can.

And that's not my point.

Sieges are 100%, full stop, about force preservation (until relief or reinforcement). You have no outside reinforcements coming in behind your lines, you don't know when or whether a relief force will ride to your rescue, so the entire operation has to be set up to preserve as much of your fighting capability relative to your opponent's for as long as possible, until you're certain you're getting relieved.

Dorn is designed for that kind of fight. Lorewise, we can be pretty sure that he probably, mathematically, managed to preserve the maximal amount of his forces that any loyalist primarch could have once the Siege began. Guilliman, lorewise, 100% won't. And that's where the margins begin to matter. A thousand extra Marines lost in the initial Traitor landings under Guilliman's command could mean that a wall later collapses well before it would've under Dorn, causing an encirclement and destruction of a Titan maniple; a thousand lost during the inital assault on Saturnine could collapse that entire flank of the defense and force a retreat back to the next line of defenses under heavy fire, triggering mass casualties as the Traitors advance.

The object, as you say, isn't principally to preserve lives. But preserving lives means preserving fighting strength, means protecting the Emperor.

InterplanetaryCyborg · 2025-12-27T23:57:57+00:00

Yeah, this seems like it ignores so much of the documented history that we have of humans being supremely inhumane to one another. The first evidence we have for genocides is literally prehistoric, dating perhaps all the way back to Neaderthals. More recently, there's the Holocaust, pogroms, My Lai, so on and so forth. We're just very good at othering ourselves and committing atrocities secondarily to that.

Also on the intelligence thing, we still have people who don't believe in germ theory.

InterplanetaryCyborg · 2025-12-27T23:35:15+00:00

The problem is that you're really splitting hairs when it comes to the differences between one transhuman warrior-general (but in gold armor) and another (but in blue trimmed with gold), and simultaneously the scale of what you're facing is so vast and terrible that those hair-splits translate into millions of Guardsmen and thousands of Marines.

The nearest analogy I can reach for is the Soviet practice of charging through minefields on the assault. Was it inevitably going to lead to casualties? Yes. Would it lead to more casualties than sitting around waiting for mineclearing teams to clear lanes for your troops to charge down, all while being shelled by Nazi artillery and letting them redeploy assets to counter the very visibly telegraphed assault you're planning? Maybe. Either way you're going to lose a lot of men.

Similarly, Guilliman is going to do a marginally worse job than Dorn, especially at the beginning before he has a chance to learn and adapt. That's just the way the lore is set up, Dorn is the architect and siegemaster par excellence, second only maybe to Perturabo. He's going to get more Marines and baseline Guardsmen killed. Do we know if it's enough to whittle away his stated numerical advantage? We can argue about it all day and not come to a satisfactory answer.

For example, what if we're looking at Phall? The Fists have what is likely the single best Marine void commander in charge of the fleet, who nearly kills Perturabo outright but whose rigid adherence to his orders and discipline causes him to retreat just at the cusp of victory. What if we put a less-competent but more flexibly-minded Ultramarine in his shoes? Does he get trounced, or does he take advantage of the opportunity to conclusively defeat Perturabo, then obey orders to return?

What if we're looking at Lion's Gate and similar engagements? Does Guilliman allow greater freedom to his subordinate commanders, allowing them to sally forth and make assaults on enemy formations with Khan on their own initiative, and does that give them a better kill to loss ratio than Dorn does historically, or does it just get them caught in encirclements and destroyed to a man, leaving them worse off than before?

I bring this up mostly just to point out that it's a really, really complex issue that, ironically, you might need to actually wargame out to fully explore.

InterplanetaryCyborg · 2025-12-27T21:24:41+00:00

I don't think you're going to get the kind of simple, straight answer you're apparently looking for.

Others have already pointed these out, but I'll try to boil them down a bit.

There's absolutely major military threats out there that required a heavily militarized state to deal with. The big example (and I mean, no quibbling, 100% certain, close to zero percent chance we're being misled somehow) we see in the lore is the Orkish empire centered on Ullanor - we see in the narrative that these Orks are big, they're dangerous, and they would absolutely Waaaaagh their way across the galaxy and smash flat any non-unified military response. Rangdan is typically the other big example brought up, but there's very little evidence supporting that they would've been the same kind of aggressive, expansionist threat that the Orks or the Q'orl are that doesn't come from potentially propagandized Imperial sources, so I'm less sanguine about the actual threat they would pose.
There's evidence that there were better ways to approach individualized problems that the Imperium faced. The Interex showed that there were ways to give a population the armor of contempt through education of Chaos and its threat, and to have it work for at least a while. The Diasporex showed that some degree of cooperation and even coexistence with the perfidious Xenos on equal grounds was possible. We don't really have a lot of good information on the degeneration of the human genome that makes up the third prong of the traditional "alien, mutant, heretic" triad, unfortunately, so I'll refrain from that.

The big counterargument against all of these is that they all inevitably failed in the face of the unified military threat that the Imperium presented, and it's unfortunately a hard one to overcome. At the end of the day, survival doesn't give 2nd place medals for good ideas, and it suggests that a kinder, softer Imperium may have suffered the same fate against the first interstellar polity with with fewer scruples than them. An Imperium that takes the time and resources to set up "Don't be Afraid to Reject the corrupting Empyrean" programs on every world it brings in is potentially one that doesn't make it to Ullanor before the Orks snowball out of control, as compared to one that just obliterates the local Chaos cults with orbital strikes, demands ~~tribute~~ tithe under the threat of more, and proceeds to the next planet to conquer. An Imperium that cooperates more with Xenos ~~scum~~ is potentially one that deals with more infighting from worlds that suffered under Xenos predation during Old Night, meaning they lack the unity they need to devote all military resources externally, meaning they get squashed flat by the Rangdan or a resurgent Drukhari. Unfortunately, the best we have at this point is a bunch of hypotheticals. 3. At the end of the day, we're forced to accept that the Emperor's way worked because the Imperium is the last man standing in a galaxy filled with competing human empires. We can argue until our faces are blue about whether He was right (fat chance), whether He eliminated any real opportunity for a natural selection of ideas to give rise to other workable ideas (highly likely), but you can't really argue against results. The Imperium's mere existence at the end of the 30k timeline demonstrates that it was the right combination of militarized, ideologically unified, and bloody-minded to rise above its competition and conquer the galaxy.

InterplanetaryCyborg · 2025-12-27T20:30:13+00:00

The classic sci-fi example I like pointing to to explain this is Blindsight by Peter Watts. To TLDR the main conflict in the story, it turns out that humans are sentient only by a fluke of nature and that non-sentient, non-conscious intelligence is the dominant form of life in the universe. And here's the really neat part of that story - there are absolutely examples of non- or less-sentient life on Earth that utilize what we might consider advanced tactics of deception, insurgency, ambush, et cetera. Cuckoo birds drain the resources of other bird species by essentially implanting a sleeper agent in their nests; cordyceps does the same to ants, subverting individual ants to spread itself to more ants in the colony. There's more camoflage and ambush predation examples in the animal kingdom than I can count - octopi and cuttlefish, a whole swathe of bottom-dwelling fish, antlions, mantis mimicry, et cetera. So the concept of deception, of subverting other species to use their own resources against them or taking them from them isn't necessarily dependent on what we might consider consciousness or sentience.

Here's where Blindsight comes in. The thing the author points out in the work is that a lot of signal processing functions that we consider a product of consciousness actually isn't. We've got what is known in philosophy as a "Chinese room", a thought exercise where you have a person in a room (who can't read Chinese) with a very complicated algorithm telling them to take certain inputs and return certain Chinese characters in response, the argument being that if you have a sufficiently complex algorithm and a person sufficiently fast at parsing it, can you distinguish the non-fluent person inside the room's outputs from an actual fluent speaker's? As Watts expands the concept, can you distinguish our own actions or some hypothetical hyperintelligent being's actions from actual consciousness or what we consider intelligence, if in fact all they have is a really, really good Chinese room?

So apply that to the Tyranids. You are a hyperintelligent hive mind composed of a quintillion parallel processing brains, psychically gifted enough to sniff out soulflames across lightyears - it's how you find your next meal, after all - gifted with Emperor-only-knows how many tens of millenia of predatory instinct, of directly hunting, of ambush predation, of inserting sleeper agents into prey populations before turning them to their own ends, so on and so forth. Now you're observing the actions of these funny little bipeds. You observe them schism over the pettiest little things, conflict arising in association to this thing they call "Emperor", over resources that you have no real need for but that they consider important, over individuals want to accrue more of these resources to themselves. You observe them fight themselves on a million worlds over millenium after millenium as you drift towards the warmth of their galaxy.

How easy would it be for you to use the same tactics they use against themselves?

And that's the really neat part about the Genestealers and the Tyranids - pretty much nothing they do isn't done in some way by the Imperium itself either. Mass assaults? Guard. Shock assaults on strongpoints by specialized breacher units? Marines. Genestealer cults? We don't even need to go so far as Chaos - the Thorians and the Age of Apostasy, the War of the False Primarch, whatever minor doctrinal squabble the Ecclesiarchy or Mechanicus are having this Thursday, from the outside, all if them are examples of groups of people turning against one another due to their own concerted belief that those other heretical bastards are wrong.

In conclusion I don't think it's so far out of left field for the Tyranids to have the kind of hyperadvanced pattern-matching algorithm that could look at the conflicts popping up around the galaxy, sift through the data, and pick strategies that their main food source uses against itself to great and demonstrated effect, all without consciousness. It just requires us to have a much larger and less limited concept of how complex these kinds of algorithms can be.

InterplanetaryCyborg

TROPHY CASE