What Happened To The Unknown Primarchs? - 40K Theories

Two of the 20 Primarchs were erased from the annals of Imperial history, but why?
For the Primarch assassination theory, click here:
• (OLD) Were The Lost Pr...
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[@mrsplitfoot23]

Apparently, during Horus' spirit journey when he saw the primarchs in their tubes, Horus touched the eleventh tube. It's possible that that very touch, caused the taint of chaos upon this Primarch.

[@Wimpiethe3]

But Horus was not yet a servant of chaos at that time, that choise came at the end of the spirit journey. So could he really taint the primarch while not really being chaos tainted himself? I doubt it.

[@zukasasteam4631]

Well chaos was infecting horus at that time and that touch could very possibly have transfered that. I mean Xaphen just had to hit the field with a energysword to start everything that led to this point. So I doubt you need more than a listening interacting person to trigger such things.

[@K4inan]

Touched the tube, not the primarch lol

[@Gutenbergler]

gray ghost it should also be noted that the 11th Legion's primarch is shown in the array of primarch faces as having a large gem coming out of his forehead. That could have something to do with the touch of Horus

[@gabrielm.942]

grayghost that’s a pretty good theory. But since all of them had already been tainted I doubt it.

[@StylesV13]

Vulkan also backs up Fear to Tread. When asked why he didn't say anything about Konrad Curze. He says " None of us wants another sanction, another empty pillar in the great investiary, another brother's name excised from all record. It is shame enough to bear the grief for two. I have no wish to add to it, but what choice do I have?" This suggests that the two lost Primarchs were unstable and flawed, worse even then Curze himself. The Thousand Sons were kept around because the Emperor needed Magnus the Red for the Golden Thrown.

[@typhoonoftempest]

Yes, Curze and Angron both had circumstances that were edge cases, and capable of being excused (Curze being left alone for such a long time and Angron because he was enslaved and kept in check). Magnus, being the most powerful psyker of the lot, as you said was REQUIRED for the Emperor's further aims regardless of the horrible mutations or other Bad Things that possibly could befell them. The Thousand Sons being as unstable as they were was an unhappy thing to have as it meant one legion was basically worthless, but had to be kept around in a meaningful fashion because (as how the warp works) Magnus' happiness is proportionate to his effectiveness.

[@thomascoolidge2161]

In addition Magnus and Sanguinius were both terrified that their mutations were going to lead to them being expunged like their brothers. Magnus sacrificed his first eye to stabilize the mutation in his Legion. He hid the fact that the mutation still existed and was trying to repair it before the Emperor discovered it and had his Legion expunged. Sanguinius hid the red thirst from the Emperor and everyone again for fear of being expunged like the two missing. With Curze it was not a mutation that was his problem yet a psychological one. He was just insane from his upbringing and his constant nightmares brought by visions of the heresy and his death. In any talk the primarchs have of the two unknown primarchs they all show regret and sadness. Few show understanding and all wish that something else had happened.

[@Emidretrauqe]

@Anubitek but where was it thrown?

[@RocketHarry865]

@@thomascoolidge2161 I wonder did the Ruinious Powers cursed Magnus and Sanguinius to make their geneseed to become unstable to be used as bargaining chips to make it easier for them to corrupt.

[@mikha110]

You do know the most powerful Psyker of them all was Leman Russ, for sheer raw power. It's how he was able to break Magnus's back when they burned prospero if I remember right? His raw power completely nullified Magnus' powers in that confrontation, on the rare occasion he would reluctantly unleash it, being afraid of the power he has.

[@AsbestosMuffins]

"My primarches cannot betray me!" "also we don't talk about those 2 primarches that betrayed me." Make up ur mind Big Emps

[@walterlopez5054]

ok, new Theory. what if the 2nd and 11th are responsible for EACH OTHER'S destruction? if one went traitor, and the other died fighting him? and they were both erased from record to keep what turned the traitor secret?

[@serioushamster]

We know one legion and primarch was destroyed by the others.We dont know anything about the other one.

[@maneon1016]

My story is something like that.

[@graemecollin]

This is kinda my theory - One Primarch/Legion turned on the other, for reasons unknown, and was duly censured, by the Emperor, using Russ and his Wolves. The remaining brethren of the other Legion, now Primarch-less. were subsumed into the ranks of the Ultramarines, but both stricken from Imperial records, to hide the deed. This, in turn, leads to a very interesting suggestion that the Ultramarines' gene seed is not, in fact, pure Guilliman, but a hybrid of his, and his lost brother's ...

[@joshuacrane2397]

@@graemecollin that could explain why sometimes I feel like Guillieman is living with some serious guilt, and not just because he didn't see through horous soon enough to stop him. What if one legion turned on the emperor before the heresy and the emperor sent the other to purge them and those dudes have since been lost in the warp or stranded on a space hulk. I've also go a theory that the missing legions were the first to encounter the tyranid and got obliterated but the emperor his it from mankind because he knew the threats that were coming from the warp and knew we weren't ready for the tyranid.

[@Werrf1]

That would explain why one was censored, but why would his victim be obliterated? I prefer the idea that they got so caught up in a petty rivalry or internal politicking that they lost it, both went mad, and started their own private war. By the time the other legions could intervene, both Primarchs were dead, and had utterly failed in their mission.

[@jordanwhite8718]

I wonder if we’re dealing with a man in black situation. Maybe the second and 11th legions we’re struck from the record so that they could perform some top-secret jobs.

[@MWH12085]

That's my theory. Possibly a part of the Terrminus Decree. I do believe they were task special assignments because the running theories (geneseed flaw, treason, ect) don't add up. Maybe it was these two who The Emperor trusted most.

[@EidolonSpecus]

@@MWH12085 Or maybe it's possible that they did not fall to chaos; but rather that they commited an even greater sin in the eyes of the Emperor: *_anti-imperialism._* The two lost primarchs may have been the punks/hippies of the family. The Emperor was absolutely convinced that humanity could only thrive if it was "united" under one single galactic empire. Separatism and independantism was a threat to the very foundations of imperialism in the first place, before chaos even came into the picture.

[@MWH12085]

@@EidolonSpecus I never mentioned them ever falling to Chaos. Even then, that appears to be the edgy boy thing to do.

[@TobeWilsonNetwork]

Definite Randal Flagg situation, outrunning that Gunslinger

[@albertor.6635]

That make alpharius look like child's play then lol

[@elenorefangirl3389]

One of them is in the throne room in Custode armor.

[@InquisitorThomas]

And the other is leading the Blood Ravens while doing backflips in Terminator Armor

[@matteussilvestre8583]

Inquisitor Thomas So they finally managed to steal a Primarch?

[@방탄수도사]

"And the other is leading the Blood Ravens while doing backflips in Terminator Armor" - Huh, sounds like a childishly cartoon like attempt at a DOW game! But that can't be right, there is only DOW(and add-ons) and DOW2, can't wait until they make dawn of war 3, hopefully they will make it like Ultimate Apocalpse mod!!

[@toxicmongerofthehatefulbro5745]

Since you found one, I stand before you and implore you to find Daddy Dorn. It's not like we miss him or anything, but he said he was leaving to get some milk almost ten thousand years ago...I-It's not like we failed him or anything..Oh Emperor did we?...*Looks for Painglove*

[@Matt-md5yt]

DORN IS THE MAN IN THE THRONE ROOM!!! HE LOST HIS HAND FOR HIS FATHER!!!

[@thezeitos469]

I had the following idea for a nice plotline surrounding on of the primarchs: Imagine one of the primarchs was send on a exploration mission beyond the boarders of the galaxy. A mission so secret that his name had to be purged from history. He travels with a gigantic fleet through the void. He even carries 4 "Hive-Ships" with him, basicly floating mega-cities. Inside those hive-ships the human workforce builds or repairs equipment from the massive amount of raw material he took with him or grows crops in specialised environments (and repopulates). Because his Legion is on his own, its bigger then even the old pre heresy Legions. But he also carries big amounts of normal human fighting forces with him in the hive-ships, aswell as a contingent of the Adeptus Mechanicus, positioned in one of the hive ships (a forge hive ship). This travel was difficult as every material lost was irreplaceable. So they were constantly under pressure of this clock ticking. But his journey was not a lucky one, as he met a Tyranid hive fleet. The battle was won and the fleet eradicated but the loses were high. So high indeed that the next encounter with the tyranids was a unwinable one. The battle was devastating. They lost an entire hive ship in that battle. Several battle barges and more smaller cruisers had to sacrifice themselfs to allow the rest of the fleet to flee. Beaten and angry the rest of the fleet returned to their galaxy. He even had a short encounter with the silent king. They noticed a ship of unknown kind flying past them in a distancet. The primarch decided not to shoot at it, as they already were fleeing from the tyranids and didnt need another enemy. Now after a few less then 10 000 years the primarch has returned. He lands the remaining Hive Ships on almost empty green planet, turning it into a hive world in the blink of an eye. Then he instantly made contact to Tera. He wanted to talk to his father after all those years. A return like that would have a massive impact on the empire. Even if their original numbers have dwindled, it still is a massive reinforcement for the empire. (several 10 000 of Marines and a primarch) And even better they brought ancient tech with them, that today has become a rarity and even some special technology, that has been created only for this journey.

[@spaceman9599]

If the Tyranids absorbed a Primarch's DNA ...

[@vojtechhykys1466]

Damn... that actualy makes an uncomfortible amount of sence

[@mattkennedy9308]

My personal theory is a variant of that might have happened to the 2nd (Lost). All the Primarchs have varying degrees of psyhic power, but imagine an Primarch who is a blank, a Sister of Silence, a Pariah. A Primarch who wields the Null as powerfully as Magnus or Sanguinus wielded their psychic gifts. Big E would want him but Magnus nearly destroyed the Imperial Webway, imagine what the Second could do to the Webway or Astronomicon by accident. So he took his legion and circles the Imperium, the first line of defence against the Void and the unexplored zones, unable to return before the Imperium is ready because they depend in psychic powers to function.

[@thedyingmeme6]

*terra

[@jadak100]

Kitten: but what happened to your lost primarchs? Emps: we don't talk about them.. Kitten: why? Emps:because we don't talk about them. >:(

[@giovannibini6809]

because i'm the motherfuckin' emprah and thus i'm allowed to do this!!

[@EidolonSpecus]

Note that they are usually mentioned as "traitors", not "heretics". It's possible that they did not fall to chaos like Horus' followers; but rather that they commited an even greater sin in the eyes of the Emperor: anti-imperialism. The two lost primarchs may have been the hippies of the family.

[@N1njaSnake]

My bet: the two legions were a taste of things to come in the Heresy: one legion turned to Chaos and the other fought it. At that time it was seen as unbelievable that one brother would have good reason to turned against the other. Thus the Purged is the traitorous legion and the Forgotten is the one which destroyed it without the Emperor's orders to do so.

[@GingerChodeBalls]

Considering none of the Legions knew the truth of Chaos, I find it hard to believe that any of the Unknown Primarchs would have fallen :/

[@adampoultney8737]

Imperial citizens can be enlightened by Chaos...

[@GingerChodeBalls]

True, though I would assume the one's doing the purging would then learn of it themselves..

[@adampoultney8737]

The most important servants of Chaos sometimes don't even know that they even serve Chaos at all...

[@TheHobgoblyn]

It doesn't need to be the Chaos gods at play for them to go traitor. The Empire was on a genocidal purge of the galaxy, not just of xenos but of all human cultures that differed much at all from the Emperor's visions. You don't see any non-European cultural influences across all of the Imperial worlds in WarHammer 40K. So a traitor legion could well have turned on the Empire out of moral conviction and honor. That is most definitely something the Emperor would want purged from the records.

[@williambibens4508]

They both fell down some stairs.

[@madMARTYNmarsh1981]

William Bibens falling down the stairs is no joke. I have severe nerve damage due to falling down stairs. Tricky buggers.

[@SamuelJS4]

Martyn James exactly, it’d be even harder if you’re wearing several hundred tons of armour

[@garvielloken9356]

I'm currently searching for the lost primarch.

[@Sigmar_Heldenhammer]

Garviel Loken *mumbles*

[@AFMR0420]

That happens to pregnant primarchs.

[@timelordjenkins7451]

There is actually real life history we can use to explain the loss of the two legions. The Roman IX. Although unconfirmed, it is widely accepted that Rome removed all records of the Roman Ninth Legion. Because if the idea spread that a Roman Legion can be beaten, then their enemies would multiply. It is likely that the 2nd and 11th legions were removed from records because the idea that a Xenos race could be so powerful/advanced that it can actually defeat a space marine legion, that could lead to the morale issues within the legions/solar auxillia and humanity in general. Not to mention, slow down the crusade as caution would start to take hold.

[@twojacksandanace3847]

This is what ahppened to the 2nd in the fanfiction The Weaver Option. In the fanfic the second and it's primarch attacked the Ymga Monolith and got fucked by the Necrons and then finished the job by unleashing a Ctan that possed the primarch and thus the legion was struck from the reccords and any survivors left ended their own lives because with a Ctan controlling a primarch, even one that is imprisoned and shackeld by the Necrons could be a massive threat, the legion or elemets of it could have tunred (not that there was much left after the Necrons fucked them) but I think it was a really cool take on the 2nd, Weaver Option is a great fic and the author already hinted at the 11th so I'm exited for that down the line.

[@Janzer_]

Fanfic doesn't matter lol

[@toxicmongerofthehatefulbro5745]

Personally I like to believe it was two of your theories. One could have had Horrible Mutations and instead of letting themselves be purified, decided to revolt against the Emperor in which Russ was ordered to put them down. The other having fought in that extremely Brutal Xenocide campaign you mention, and shamed the Emperor in one way or another, like..Trying to...B...Bef..Befri...Gah...Befriend..T-The..The...Xeno... But one Legion was mention to be the Forgotten while the other the Traitor, so it could also have been that one was horriblely mutated (Again), Russ and the Other legion was then sent to purge them and the two of them completely killed each other off. After all, the Iron Cage proved that even if one Legion has amazing Fortifications, as long as they both have their Primarchs they'll basically wipe each other out unless a third Legion intervenes.

[@lordcommanderklaus1636]

Imperial Fists - befriend and xeno do not go together

[@toxicmongerofthehatefulbro5745]

I know this you walking Corpse, Yet for doing something so.. Horrible... I would understand the Emperor Purging every last bit of information on them, so it must have been said to put the Theory out there.

[@lordcommanderklaus1636]

Imperial Fists - and that is something we can both agree on

[@GregoryElliott1973]

What if one of the lost primarchs pods had landed on a lost forge world? The primarch had become the head adeptus mechanicus? Thus making himself part of the forge world itself?

[@TheHobgoblyn]

This is the same thing I am thinking. Separate tragedies-- one mutated thus causing other Primarchs to hide the mutations in their own legion, the other turning traitor but not because of Chaos influence-- simply because the Great Crusade was too unjust and brutal.

[@timothypeterson4781]

I like to imagine the two lost primarchs realized that the Emperor was actually a genocidal sociopath and decided to tell him to screw himself without having to fall to chaos to do the same. (Or at least one of them did.)

[@Nat-kq2oe]

do you think that the lost primarchs could have refused to join the emperor outright. and so were purged along wither there worlds

[@zenoblues7787]

COMMIASSR NAT or perhaps they left the galaxy and the Emperor just made it look that way it is after all implied that the Tyranids for all their power are running away from something out there beyond our galaxy

[@MrTurbowhitey]

That's the Idea hat holds the most merit to me. That the lost and the purged where brought up on independent and proud worlds that wouldn't bend to the Tyrannical rule of the Emperor.

[@DEMONX62]

angron refused to join

[@Toto-95]

And maybe this time the Emperor got sick of it and teleported him anyway on his barge

[@pyrosauria7444]

COMMIASSR NAT seems the most likely of things to happen, it's also could be possible that the Emperor founds the traits of he primarchs to be undesirable and purged them for this.

[@DefectiveFish]

Here's a thought, what if one of the Primarchs had become obsessed with AI tech?

[@TheByrd1220]

Maybe the lost Primarchs went AWOL in the warp or something

[@MadRoadDriving]

The Byrd I've always been a fan of that theory. One of the lost primarchs simply disappeared into the warp at some point, with a chunk of his/her legion. That would make them "the lost" The other one, however, pulled some shit.

[@wesleydannelley297]

I feel that the two Lost Primarchs are going to be used by GW as something they can introduce at later times to add freshness to the franchise. The reintroduction of a lost primarch in a great time of need for human kind would be a pretty good story.

[@Matt-md5yt]

THANK YOU FOR SAYING THAT NUMBER 11 COULD HAVE FEEL TO MALAL/MALICE! just really happy you mentioned it. (now in Character) ELEVENTH WAS BAD THE SECOND ONE IS DEAD BECAUSE OF HORUS!!

[@jamesrose1460]

I would agree here in that the 11th Legion were taken by Mallus/Malal...I had them...As the Star Guard...led by Toryn Rohja as Primarch...a Space borne legion who vanished into the warp during the mid 30th Millenia...returning in the 40th as The Taken...Mallus/Malal Chaos Marines who served him in his great crusade to kill the 4 great Chaos Powers. They were the true Death Marines...even having their armor sporting Adamantium Skulls as the faces of their helms...not just painted on. Their colors were Black, Silver and White. The rode arround in a Great Crusade Era Grand War Barge...THE IRON SUN...which also related to their emblem a Silver-Gray Sun with a Black Shield imposed upon it. Was a fun time...working all the background up for this idea. :) Just wish most of it had not gone away when my HD died.

[@MRDLT00]

All praise Malal! :D

[@themorrigan4409]

I have been playing with the idea of one of the legions escaping into the human webway. They managed to contain it using their inherent abilities as blanks to salvage and repair a piece of it and have been floating in the webway as a shadow observing everything going on on the outside occasionally sending out warbands to carry out their primarch's. The Emperor and by extension the Imperium sees them as renegade, they have always and still do fight for the people, though they are now forced to work outside the law so to speak, building an elaborate and complex spy network that includes other renegade chapters, rogue traders, nobles and governors, and even some xenos. But now that the eye of terror has basically divided the galaxy in half following the fall of Cadia (tearful salute) they are now faced with a dilemma. Do they stay out of it and hide in their webway home only to eventually be destroyed by any faction that eventually stumbles upon them anyway? Or do they come out to try to slow the spread of the eye of terror and potentially expose them to those who may still wish them dead? Either way, many carefully forged alliances could be shattered and their elaborately created spy network potentially destroyed.

[@doorstopper674]

What if the space marines they send are the legion of the dammned?

[@runcmd1419]

A chapter with no insignia or regalia would be cool, just solid black armor to represent their expunged state.

[@Ajehy]

My theory (on who they were, not how they died): at least one of the Lost Primarchs was a naval specialist. As in, actual seagoing ships. We have assault troopers, we have infiltrators, we have fast-moving bikers & siege-masters... The lack of a Legion that specializes in such an important and obvious form of warfare is otherwise baffling. Perhaps a Polynesian theme, with haka war chants and amphibious assault Rhinos? That would be badass!

[@inmamata]

I distinctly recall Russ saying flat out that he has the "most" experience killing primarchs(during the Horus Heresy series) - and this was after he learns that Fullgrim killed Ferrus Manus .

[@goodwin9114]

If covered by anyone before I apologise. The fact 21 chairs were left 1 for the Emperor and 20 others one for each Primarch and theres only one seat for the Alpha Legion suggests it wasnt common knowledge that Alparius and Omegon were twin Primarchs. So when Isfrael tells Zahariel The Lion has 19 brothers he can not be counting the twins in that numbers as a) the Alpha Legion were all about secrecy and b) the Dark Angels were all about secrecy. Isfrael wouldnt be passing on sensitive information to a relativly junior member of the Dark Angel Legion surely? Alpharius also went by the name " the Threefold Serpent" possibly suggesting a link with a third Primarch. Also at some point several of the Primarchs have been cloned in one shape or form yet the two missing Primarchs have not- that we know of and within the Galaxy no suitable figure has come forward to suggest they could be in the frame which suggests a very very thorough removal, almost like what The Emperor inflicted on Horus at the climax of the Heresy and even then Horus was subsequently cloned later down the line anyway. If the Emperor had erased them for treason etc why would Guilliman wish to honour them? The Imperium likes to honour fallen heros so seems unlikly that two Primarchs would be striken yet the Dark Angels whom were also present would be left alone given there part in the Rangdon Xenocide. Didnt Horus strike the second gestation pod in the Vault beneath Terra during his Heresy inspiring vision with Sejanus(Erebus) causing hairline fracture on the pod. Would this not compromise the pod during The Scattering possibly opening the way for the occupant to be corrupted (Lost)? Also The Legion of the Damned (lost) with a nod to Lithiumjuice Artwork below. It turns out I am a geek.

[@TheWickerMan1981]

Since 2nd, I always assumed it was meant for the players to be able to role-play their own chapters with a primarch in their own lore.

[@tengkualiff]

Love these theory videos because it gives so much possibility for GW to attempt to release small details about these two Primarchs.

[@DanielSan1776]

A cool possibility could be the Emperor found navigational data from The Old Ones, or the Necrons regarding the deep core. He sent one or both of them there to create a small human empire that no one else knows about to ensure the species survival should the Imperium be wiped out. Also, i love how ya’ll source the info during the video.

[@stuartrandall126]

My theory had always been one Primarch had been kept on ice in case of a situation so dire the emperor unleashed them as a final solution. The other embraced the nature of death and became the controlling force behind the legion of the damned.

[@doorstopper674]

I like the idea of the legion of the damned being the lost legion

[@godemperorofmankind7255]

What unknown primarch.......there are no unknown primarchs..... (suspicious tone). No Ferrus Manus, your acting suspicious. And why are you here anyway you floating head. Cough....Inquisitor.....assassassinate any witnesses.....cough.

[@jerec1267]

YOU ARE WEAAAK GOD EMPEROR- skost of ferrus manus m41

[@MrTurbowhitey]

Yes Ferrus, we know.

[@godemperorofmankind7255]

+MrTurbowhitey You don't know nothin. None of you do!!!

[@Animoos20]

God Emperor of Mankind I might

[@60sSam]

Magnus The Red Neeeeeeeeeeeeerd.

[@KaiShanIV]

Back a few decades ago I read an article/interview where one of the creators said they left two slots open for players to create their own chapters. That being so, they will never be named by GW but there will be thousands of claimants made by us; so go create your own chapter... mine always turn out to be Ultramarine successors anyhow.

[@schro34]

Maybe the on forgotten didn't want to join the imperium and the purged one was the one that was wiped out during the great crusade

[@zenoblues7787]

I have pretty much the same opinion

[@schro34]

I mean it does kind of make sense since they only said they failed but they didn't say they at what. So it could have ment one failed in combat and the other failed just because he refused his father so it was decided that he was to be left alone and forgotten

[@UncleFester84]

The Purged one: faced mutations during the great crusade thanks to a Rangdan weapon that exposed genetic imperfections and those affected, primarch included, had to be 'sanitized' by Russ. The Forgotten one: after the xenocide he became disillusioned towards the Emperor and the great crusade and took some of what was left of his legion plus a siezable amount of people and escaped imperial control, and maybe the galaxy itself, in hope to found a colony based on peace. That or he began being worshipped as a god by the people and he came to believe that he was one. What do you think?

[@Jagrofes]

An update you can add to this, the 2nd and 11th Legions are confirmed to have participated during the Rangdan xenocide. The Regimental standard “Field dressing a Lasgun Wound” confirms this in an image of the guide.

[@40KTheories]

Funnily enough i'll be talking about that in a future video about the deeds of the unknown Primarchs along with some other notes ;)

[@ballista100]

I always liked the idea that forgotten had been sent away by the Emperor when he recived visions of the heresy as a sort of congitgancy and the primarch was told to return at a certain, and only the wolf whose loyalty was without question knew the truth and provided a reason for the legions disapearance.

[@johnsemeniuk8230]

On your idea of Custom Legions... when my only actual experience with the Space Marine video game, and I learned of the Lost Primarchs, I went and made my own Legion. Never used it, but it was a fun little thing to make. Only experience with 40k remains Space Marine, and the Lexicanum wiki. And videos like this.

[@robbybeckmeyer828]

Still a big fan of the idea the 11th legion fell to chaos (specifically Malice) in an ironic twist due to the 11th were meant to be a specifically anti-chaos legion

[@robertoluna6606]

Back in the days i wrote down my own story about the lost primarchs, something very simple, with a really good primarch and a really bad one. As of now, i loved Remleiz's story about Sigmar as a primarch, so i'm keeping that as a piece of personal lore, although i want to modify AoS lore to make it fit into the homebrew lore. Still trying to think some interesting 11th primarch to put with Sigmar. Any ideas?

[@fjLKA]

Archaon.

[@kiesarisunny13]

My Chaos Warband is the 2nd Legion, they went farther then the rest of the Imperium’s forces during the Great Crusade and got caught in a not chill warp storm that threw them into the Warp, they then were attacked by Khorne and Nurgle Daemons and were, nearly all killed when Bel’kor saved them and made them believe he was a god, they have taken a few worlds outside the Eye of Terror during the Plague Wars and are using them to hold their GeneSeed as their Primarch having become a Champion of Be’lakor

[@Ghaztoir]

11th legion belongs to Malice

[@eli8444]

Ghaztoir It is his number. I'd like to think that the second legion receeded into a mindset that started a second Dark Age of Technology. The Men of Iron were no fucking joke.

[@_brushie]

I do remember a quote about the Thousand Sons being on the edge of being expunged like the other two Primarchs before Magnus was found. I'm trying to remember the book, I think it is around Prospero Burns.

[@jipowap]

Might be the Forgotten turned away from war or turned to a chaos god of Order like Alluminas. That he would not fight for the Emperor would be seen as a failure.

[@pepenero6168]

jipowap47 who's alluminas

[@animemanXLK]

I think it could be that one or both of the lost Primarch's fell to chaos either when or very shortly after they were discovered except in these instance/s being relatively smaller in comparison to the Horus Heresy the Emperor decided to keep it secret from the Imperium at large and had them erased from Imperial history records to try and keep knowledge of Chaos and it's temptations away from others who might be corrupted by it.

[@Aravaganthus]

One of them was born a girl, and Big E was all like "eh, no, not bothering finding that one, girls are icky". The other was a ginger, and Big E was all like "eh, no, not bothering finding that one, gingers are icky".

[@insertedgynamehere]

I was looking for a comment like this

[@copudesado]

IMO the two primarchs did something that undermined the imperial creed. Maybe they started *gasp* cooperating with xenos and building a quite functional society that way, like the interex did. Or maybe one started using mutants in their society. The emperor would not want these stories coming out as they undermine his vision for a totally human galaxy.

[@Rikhardt99]

Ngl, Malice being one of the lost primarchs sounds very interesting.

[@roguepsykerhaaker4813]

I always liked the idea that at least one of the lost primarchs was a psychic blank of immense power, and more importantly control. And I also like the idea that he was created to essentially judge the emperor, to act as a spotter if you will. To be beyond the emperors meddling and in a position to directly stop him if he ever went off the deep end, but because of the scattering he couldn't be raised in the way the emperor needed him to be to be a fair judge and was purged. The other is, uh, a girl because why not

[@Ianassa91]

I used to be primarch like you, then I took an arrow in the knee.

[@SuperUniverse]

There is a possibility that the lost 2 primarchs had something to do with chaos since the only time the emperor is severe with anyone is when it involves religion or chaos. Or the 2 primarchs are simply disillusioned with the Emperor's grand plan and decided the break off .

[@emperorofdenmark8081]

Maybe one of the Primarchs was Omegon? Or Alpharius? Or something to do with the Alpha Legion

[@teroslarone1171]

Emperor Of Denmark Those two haven‘t been found at that point.

[@theannouncer5538]

I never noticed how there was someone standing behind Alpharius in the portrait

[@OgamiClan]

It is Omegon. Or is Alpharius?

[@pyrosauria7444]

The problem I have with Master of Mankind is that it's very contradictory to the Emperor behavior of the primarchs throughout the series. He's shown to have care for many of his sons such as Horus, Sanguinius, Magnus, and etc. Sure, certain primarchs such as Angron were disfavored but they weren't left to rot not to mention that the Emperor did save Konrad from having a total psycher melt down and etc. However if I had to make a guess as to what happened to those two...It's possible that one may have been raised on a Xenos world as there's a possibility that the primarchs could have landed on such world (Tho I'd image if one of the Primarchs landed on Ulinor, then that would be a "good fight" for the Orks until the Primarch child was eventually killed and had his skull mounted on a spear). Basically said Primarch would harbor xeno sentiment and either stay with the xeno brethren to defend them from the onslaught to come from the Humans or join the Emperor and work to make xenos acceptable in the Imperium. This obviously would go against the Emperor plan so...This necessarily wouldn't exactly be the case but I do see any Primarch that denies the ideas of the Emperor to be somewhat too problematic and had to be executed. Like say a Primarch who was big on Democracy or the People in general and found the ideas of a Dictatorial Empire with oppressive nobility and strict hierarchy to be against his interests to say the least. Another potential reason for the forgotten sons would be not exactly mutations but actual handicaps such as being blind, having broken legs, deaf, and etc to be possibilities. Hell maybe if the Primarch didn't match the characteristics of being bulky and such (Like say being more skinny for agility and speed like an Elder) or potentially not developing the desired personalities (Such as someone who prefers to just be alone and/or doesn't want to wage war) being a possibility due to the fact that they simply weren't playing the roll they were intended for. This would be unlikely of reasons but still reasons whatsoever. Hell, even tho I'm 10,000 years old, I seem to have forgotten of those two...Wonder why... :/

[@bobmarine7392]

Pyroskies You are 10,000 years old ?

[@pyrosauria7444]

BOB MARINE yes actually, I'm a perpetual. :P

[@adampoultney8737]

Try an indeterminate amount of time! I'm Tzeentch!

[@lordinquisitorsec7532]

Pyroskies What if one of the Primarchs hadn't been found by the Emperor? Or ended up on a Tomb World of the Necron race.

[@TheHobgoblyn]

If a Primarch had never been found, then there would have been no Legion for them. They certainly wouldn't have a specific numbered legion, it would just amount to the Primarch themselves never being mentioned. But the reason there is a mystery is because 2 of the original 20 Space Marine LEGIONS that once existed and certainly once originally had a name are missing, not just random sons of the Emperor that were created but never again had contact with him. If they either sided with or were wiped out by a Xenos race, it would have been after there was a whole legion of them.

[@thewerdna]

My theory is that the Rangdan were responsible, in that its hinted that thr Rangdan posessed powerful psychic abilities. What if they mind controlled the two lost primarchs? This would explain why some would consider them traitors while others would consider it a failure rather than a willing betrayal. Russ would still be the one tasked to put them down in the end.

[@williamamely7038]

I believe that the 11th Legion's Primarch and his Legion turned Rogue, believing that the Emperor was a Traitor, as the Primarch found out of the deal made between the Emperor and Chaos (whom the 11th had battles with befor the Emperor found the Primarch. The 2nd Legion was devotely Loyal to the Emperor, but the Primarch suffered a mutation that caused the Emperor to loose trust in him and censured the Legion by ordering them to return to their homeworld and not allowing them to continue in the Great Crusade. Most of his Legion (80%) was split between the 13th and 7th Legions. The rest was allowed to remain to protect their Homeworld and the worlds in their sector. The 11th, however, disappeared. Their entire Legion and fleets were nowhere to be found. Unbeknownst to all, the 11th had forged their own empire within the Imperium, with over 9000 worlds under their rule. Additionally, they have been fighting Chaos these last ten millenium and have invaded Chaos' rhealm numerous times and their ranks now number in the millions of Legionaries.

[@godseeker9]

What I get from reading the novels is that they encountered strong mutations and they were purged as failed. The first ones to get a taste from this "Purging" were the thunder warriors. Although good at their job they were exterminated due to their volatile physiques. So we can safely hypothesize that the Emperor took exactly the same measures for legions that were abominably mutated. And it could happen as most of the legions are imposed to mutations

[@PCveteran117]

They were probably DOA and the Emporer sent their legions over to the Ultramarines after discovering this.

[@joecole5545]

Then why were their statues torn down?

[@PCveteran117]

Joe Cole The legions may never had a Primarch to begin with.

[@DioBrandoWRYYYYYY]

the thing about why Big E might have not wanted to destroy the Thousand Sons due to defective gene seed is maybe he made exceptions for Magnus because he was the second strongest psyker in the Imperium which made him an extra valuable asset to have on retainer even beyond just being a Primarch

[@1985Cyrus]

That was what I thought, Magnus was to sit on the throne and the sons were to power it so Magnus could just focus on keeping the webway secure from Warp breaches. That way Big E could go into the webway and get some sweet Eldar booty.

[@allendillow6658]

I enjoy the thought that the Lost and the Purged were quite that. The purged is when Leman and his wolves were loosed upon another legion (likely due to mutation). The lost was simply that, lost to war or some warp-fuckery.

[@bobmarine7392]

Emperor open the PORTAL and send them to the place where they can't be found

[@Matt-md5yt]

LIKE IN FANTASY OR IN BERSERK?!!?!!!

[@bobmarine7392]

I think it Fantasy

[@Sigismund697]

I was reading Fulgrim the Phoenician the other day, there Fulgrim meditates how his brothers even those found after him, don't consider him ready to take his legion out by themselves, he even comments on how the taciturn master of the second spoke against him despite him rarely doing so What I found interesting was that whatever was said was negative and Fulgrim remembers a Terran saying of pots and kettles which makes me think that the second legion had some dirt on them already

[@darkmystic7764]

40k Theories, also known as the Malice Theories. :D

[@Nyj]

I personally like the Idea, that both Legions suffered heavy mutations (Like the Thousand Sons or the Blood Angels) and both tried to cure this mutations with the help of Technology, like the Men of Iron. One of them was destroyed by their own experiments (The Forgotten) and one was more ore less sucessful, abadoning their flesh and were purged for this heresy. In Warhammer 40k, the Humans have a strong aversion against Artificial Intelligence and the cybernetic revolt during the Dark Ages of Technology, are considered more brutal then the Horus Heresy, so it would make sense in my opinion.

[@Lau_wings]

I remember hearing a rumor once from a GW employee (in store not high up etc) that Dan Abbnet was given permission to answer the question of what happened to the two lost Primarchs but he couldn't come up with a satisfactory answer so the idea was killed off. Gotta admit this rumor sounds plausible to me as anything other than perfection, which would be impossible for everyone, would be rejected and people would hate/be disappointed it.

[@robskovira5626]

One could be the giant in Baroque Power armour in Trazyn's museum. I forget actually where I read it, but there was a mention of the 2nd legion fighting Necrons during the crusade.

[@tomasstrasak740]

1:20 Leman Russ: You should spend more time beeing raised by the wolves

[@lesROKnoobz]

I think it sounds most plausible that they were killed / defeated during that war with those super tough xenos during the crusade and that the emperor considered them failures for their deaths / destruction of their legions

[@Mouth17]

is Russ back, or is it just being speculated because Magnus is coming back and Russ would likely return for him?

[@stephen19590]

Mouth he's still in the warp, although with cypher doing his thing I'd say the lion could be back perhaps, then against mortarion is also coming back

[@Mouth17]

I'm only recently getting into warhammer lore. not a player but a big lore fan, I've been absorbing as much as I can and listening to horus heresy books

[@stephen19590]

Mouth well essentially the story is moving forward, primarchs are coming back, the eye of terror is bigger and more and more things find human life quaint, the lore is pretty complicated cause there are very few confirmed things lorewise

[@novakayne9373]

ive not read into this much, but my theory is a primarch was sent to mars where he grew up a tech adept and converted himself fully to a mechanical being (the reason why Martians dont turn fully mechanical) and his legion became the men of iron (supporting the traitor theory and the genetic failure as supported by sanguinius)

[@darthplageous5412]

It's possible the remnants of the 2nd and 11th legions did fight with Horus at the begging of the heresy while their Primarchs had already been destroyed. Unlikely but just a thought that it may not have been a retcon.

[@hadesolympuse2870]

Now this is purely speculatory theory. What if the 2nd and 11th legions, the forgotten and the purged are the grey knights and the legion of the dammed respectively. As the knights where "forgotten" by humanity as a whole till the founding of the inquisition when they were discovered with a massively over filled chapter of battle brothers. And as for the 11th, the legion of the dammed are said to be ghostly warriors of flame that come only when astarties truely need them most then vanish without a trace once there task is completed, they could have been so corrupted by chaos in body that the emperor purged there bodies then preformed a ritual similar to the rubric to fuse their souls to their armor. This theory doesn't give us any information as to the identities or status of the lost prime-archs but it could make sense as to the reasons for these twos existence. I will do more research to try to find out if this is passable or not.

[@kevinaustin51]

The real reason there data was expunged form imperial record is that Billy and John didn’t quite fit the branding.

[@epiendless1128]

They fell in love with each other, and lived happily ever after.

[@BrenttFease]

I think it's especially noteworthy that Guilleman insisted on having places for them at their table, particularly his reasoning for it--due to honor demanding it. This implies that the reasons they were expunged from Imperial records was due to something that didn't completely remove their honor. My theory after seeing this is that their loss was due to some sort of great sacrifice, in a circumstance that the Imperium couldn't learn of for its own good. This couldn't have been Chaos related necessarily, since the concept of Chaos wasn't really well understood by anyone at the time, but it could have been other things. Perhaps, for example, a particular Xenos threat was so dangerous that they were forced to pretend to betray the Imperium so they could destroy the threat from within the enemy ranks, thus prompting the Emperor to expunge them from the records as a way to sell the story. Leman Russ could have been the one to finish off those who refused to go along with the plan, or who viewed the self-sacrificial orders as a betrayal and went renegade. Purely speculation, of course, but that's my thought after watching all of this information put together.

[@dalgreth6061]

Well the Primarchs have some sense unity among each other that separates them form their father. So while the 2 lost Primarchs had been removed by decree of dad, they most likely were not in agreement with him. I would say the forgotten one was more of a shameful dismissal or were served a punishment that went worse than intended (similar to the 1k sons rubric that they cast), and the purged would be referencing an event where the Primarch was slain by one of the remaining Primarch by order of the emperor or even by himself.

[@robertorodriguez9854]

I remember in a thousand sons Lorgar snaps to russ "or what! you will strike another brother!" in which russ hesitates, leading to the idea that russ did eliminate or executed the other primarchs

[@Yusuf-fs4fn]

At this point he had struck the Lion. He even says the Lion's name in the passage actually.

[@lukewarren8227]

Okay, personal theory, but what if when Horus touched the 11th capsule, it removed the primarch’s soul, making him, and all of his legion, untouchables. This would make him him a great threat to the Emperor, due to untouchables being anathema to psykers, causing the emperor to send the Space Wolves to destroy them, wherein the 11th were either destroyed or escaped to the warp (where such numbers of blanks would leave themselves invisible to daemons and the chaos gods.) And the 2nd Primarch likely died in the Rangdan Xenocides, which would be a huge blow to imperial morale if it was widely known, what with it proving that the primarchs and legions could die, which would cause the emperor to purge the 2nd from history, making the 2nd the forgotten and the 11th the purged, which also explains why Sanguinius was so scared to show any flaw in his geneseed, and explaining the legion lost in the Rangdan Xenocides.

[@kristofevarsson6903]

I personally believe that one of the Legions was the II Legion...being the Thunder Warriors and their Primarch, Arik Taranis. The descriptive titles of "Lost" or "Purged" can both be attributed to the Thunder Warriors, as their genetic instability left them lacking in longevity and prone to fits of PTSD that would put the Black Rage to shame. - and as a result, the Emperor had them culled the minute their usefulness ended at the end of the Unification Wars. However, as we all know, not all of them were culled, and Arik Taranis himself escaped along with his lieutenant and several others, eventually stealing the Progenoid Glands from a fallen Astartes that would allow him to continuously generate new organs for himself to increase his lifespan. The Progenoid Glands can also be used to engineer normal recruits into Thunder Warriors without the genetic instability as the organs would be entirely their own and wouldn't be rejected. This would allow their numbers to replenish sufficiently enough to return to Legion strength. And since neither the Emperor as a person nor the Imperium at large has ever been honest about anything that we know of outside of raw certainty that things just happen all the time, it would make some semblance of sense for the Imperium to "allow" Thunder Warriors to continue serving in the name of the Emperor in order to earn his forgiveness for not dying like they should've at Mount Ararat. I personally like this idea given what we know about the Thunder Warriors and the Lost Primarchs, and how their situational availability lines up pretty nicely. Most Imperials have never seen an Astartes anyway, and so they've become mythical creatures because of their imposing physique and superhuman characteristics, so how would they know the difference between a Cataegis and an Astartes? Especially now that Primaris Marines have come into the fold, which are also suspected of being essentially perfected Thunder Warriors given their similarities.

[@hitomisalazar4073]

Interesting thing about the idea of Russ putting down the Unknown Primarchs. In Mark of Calth one of the Ultramarines was censored by Guilliman, for the treason of even IMAGINING the idea of fighting against Space Marines, and coming up with "Theoreticals" for it. This suggests to me, that it's unlikely that Russ or any other Space Marine actually sanctioned the Lost Primarchs. If Space Marine on Space Marine action actually happened, I wouldn't think that coming up with "Theoreticals" against Space Marines would be so shocking and unheard of. After all, if Russ fell, who would put him down? The Ultramarines? They had to sanction the Word Bearers after all, so not too far outside of belief for me. I'm thinking that one of them probably succumbed to rampant mutation like the Blood Angels almost did, and the Thousand Sons were on the way to once the NERD! ramped up the Flesh Change. This could be the REDACTED lost battle damaged legion as well. Perhaps those xenos creatures having some sort of weapon that twisted and mutated the legion itself to the point of madness and disgrace beyond redemption. Considering things like the Hrud's ability to entropy field things... I don't see it as all that unusual. I'm thinking the other, being probably was an assassination. It would explain why the Assassinorum ever thought it could kill Konrad Curze or Horus (or the Emperor) as in during Nemesis: War in the Shadows. We know that the Primarchs aren't beyond mere mortals kicking their asses after all. The Lion was nearly taken clean out in a straight up swordfight honor duel against Luther after all. And if he was the first Primarch ever assassinated he probably didn't expect it nor had any primarch since even thought it was possible that they could be bested by a mere mortal or anything of the like. Heck in Unremembered Empire Guilliman himself almost gets chumped out by 10 no name jobber Space Marines. And this was with him at least suspecting the strike moments before it happened.

[@shikatsu]

Well Russ could consider it, that was why the other brothers did not like him one bit. It may have been they got the legionaries while the Assassins got the primarchs proper. He was willing to drop Angron and did not even blink when Horus changed the orders from capture to kill with Magnus.

[@tompearce8173]

I have just got back in to 40k after a 15+ year hiatus and I have been playing around with the idea of the “forgotten” primarch being a blank with the Pariah gene but as a negative mirror of the emperors own power, this would be why he was lost or purged as having him any where near a world would have a similar affect as a Psi Titan if not worse and he would disrupt the Astanomicon in shuch a way the emperor would have to have him removed before the great work on the web-way plan could take place. His whole legion would also be blanks or nulls and as such would cast fear and dread on every planet they set foot on but the there would be a very small success rate in making new Space marines due to this rare genetic flaw, so a very small legion with no also they are still stuck in the Rangdan sector or further afield in void space as they can’t use the webway to just hop back as no astropath could survive being on a ship full of blanks (probably left there on purpose by the empowers command) as a legion of Blanks would be the perfect weapon against a hyper psi-tech race. There is some wiggle room in my head cannon that the majority of the already small legion was caught by necrons and turned in to the only pariahs in the universe and this is why they no longer exist in game as they have all be destroyed and the necrons can’t find blanks with the power and strength to survive the transformation or this gene seed to be used to “clone” more powerful blanks to pilot the Psi-Titans as this project seemed to start up at around the time the legion was “lost/forgotten”. All in all I’m working on a home brew rule set that lets me field an army of blanks, it would field a very small number of powerful models with ancient and forgotten weapons from the time of the great crusade.

[@theyoda55]

I do have one idea that kinda fits. Perhaps why at least one was seen as a "traitor", but not in the Horus Heresy fashion is that one primarch grew up in a multi-specied society. He "failed" when he refused to purge xenos b/c he grew up around more that just humans and saw xenocide as an atrocious crime when the rest of his brothers did not. He still saw other species as good people. Maybe he didn't see mankind as having a "birthright" to the galaxy. That could also be why records were specifically expunged since the Imperium can't have one of it's Primarchs protecting xenos and espousing why they should be treated with the same rights as humans or something similar. As a result, he was purged in order to maintain the "filthy xenos" policy of the imperium. Perhaps when Sanguinius referred to them he wasn't just talking about mutation, he could have been talking about breaking from the Imperium's "pure human" policies in general. Perhaps they even see the act of allying with xenos as a mutation in and of itself, like a mental disorder, because none of the others thought that way. There's no book evidence for this, BUT not seeing xenos as filth that need to be purged would be something that no one would want to talk about..... ever.

[@IonicSarge]

One isssue I’ve had with the Lost legions being traitor is that in the Horus Heresy novels it’s made pretty damn clear that a Legion going traitor is absolutely unheard of. And Brother fighting brother is almost unthinkable. Horus makes this even more clear when he begins his fall and decides he needs to find a way to get his men accustomed to the idea of fighting other Astartes.

[@thehypergamer9873]

in the book legion towards the end the guy I think Natmajira said it would not be th first time a legion was to be judged for transgressions could be stuff like what angron and his legion did but who knows

[@randomwall9154]

Not sure if you are aware, since you have yet to read the Dark Angel's Horus Heresy books, but Lion El'Jonson was also lost in the chaos infested forests of Caliban for a few years, until Luther discovered him on one of his hunts into the forests.

[@40KTheories]

+Random Wall my point still stands as when Luther found Jonson he still educated and trained him becoming a father figure to him, Curze never had that luxury

[@grizzvolk]

One turned out to be an Ogryn the other a Squat. Both are on a never ending pub craw through the Imperium.

[@TheGeraltofrivia]

Alistravia (my) primarch of the 2nd went into exile because of her higher level of technology and the fact that the mechanicum saw her as an affront to the omnisiah and attempted to kill her which back fired and resulted in a war in which the mechannicum was split in two. one side sticking with the imperium and the brothers who supported Alistravia and the other half of the mechanicum forming another block along with several xenos species in an attempt to take over the imperrium. (it's worth noting sveral brothers did not assist Alistravia on princaple those were Ferrus Mannus, Rogal Dorn, Sangunius, Fulgrim, Mortarion and Puetorabo. some assisted her indirectly while Horus, Angron, Konrad Curze, Magnus and leamen russ assisted her directly) The war was lost for the rebellious mechanicum faction after it attempted to experiment with Alistravia's slip space technology and opened up a spacial rift ripping their designated capitol world apart and killing thier leadership thus forcing them to surrender and be ultimately purged. Afterward Alistravia told malcador and her father she must leave the imperium or risk another war. her father told her she must make her case in front of all her brothers as it is they who would have the strongest opinions to her leaving..... despite objections from the Khan, leaman russ and Horus they agreed to allow her to leave the imperium after she stated "Look at where I am now brothers. I am almost a hundred years ahead of the imperium so I ask you..... think of where I would be in ten millennia and tell me if you think I should stay" In order to cover up the self exile (so that other systems and groups would not attempt to do the same) it was agreed that Alistravia would be expunged from all imperial records and only her brothers, Malcador and the emperor would know the truth of it. her legion was split in half as part of a bargain with Roboute and the fact that her genetic technology had reached a level where she could now create her own space marines without the need of any help. In my fan fic alistravia is also resposible along with russ for the death of the XI primarch as she was asked to assassinate him while he was distracted by russ's attack. she used her sniper rifle the emperor had given her and killed him as he fought russ. she regretted this act afterward despite knowing what the XI had done to bring assasination upon him and had her three most senior son's (Kyros, first captain, Gigas Captain of her bodyguard and Sankara qualm her equerry and chief librarian) seal the weapon away in a locked box that could only be opened if and when the time was right.

[@Mike-8404]

Going off of how GW uses various elements of European history and politics in it's stories, it' could be surmised what happened to the other legions. When RG says the other two "failed" it could mean that they were lost during the great crusade either fighting impossible odds that got them killed and their legions wiped out, or they were lost in a warp storm never to be seen or heard of again. Just like how the Romans are believed to have lost the IX Legion

[@temogi5762]

I like the idea one was lost in the webway and the other was sent on an expedition into the outer rims, and will return when/if the emperor finally dies. Easy E liked keeping secrets from his kids so he probably told Russ to lie about killing them off.

[@sierra6echo527]

I like the wording of the 'forgoten' and the 'purged'. Taking into account that technology advanced enough might be considerd as magic and as for fantasy opposed to 40k might even be viewed as divinity the thought of sigmar beeing a primarch that was purged isnt as outlandish as one might think and the forgoten might have been sent into the furthest regions to find allys or somesuch and just hasnt returned yet.

[@GrimDankHeretic]

I wonder if both primarchs simply abandoned the crusade for one reason or another, completely leaving their legions to do their own thing and we’re hunted by Russ for it. I could see them abandoning the crusade as perfect reason to have their identities forgotten

[@jefferydunn5312]

So, given the information here, I think you were right. 1 forgotten, 1 purged. The 1 forgotten fell during the great crusade against the... w/e their names are and the other was purged for deformities as eluded by Sanguinius, by Lemun Russ. Good detective work.

[@Eclipsed_Embers]

my personal theory is that the genestealers are ultimately decended from a lost legion that had a flaw allowing for much easier gene-seed insertion with a much higher rate of success and even the ability to pass it on to offspring but the astartes and primarch were horrifically mutated and deformed, the realization that this legion could even make astartes out of xenos races including the Orks led to an order to purge them while propaganda wiped all trace of the legion and reclassified the legionaires as a xenos race called genestealers while reclassifying their mutated gene-seed as a genestealer germ-seed (that is the actual term in lore for the things that genestealers implant to make hybrids)

[@YoBadMama]

Based on the opinions of many of the other primarchs, the two missing primarchs were indeed known and liked by their brothers. Had they never been found or traitorous, they would have just shrugged their fates off as a pity and a shame, but they mostly show a sombre change of face whenever they are brought up, implying some sort of positive relationship. What makes this such a hard topic to cover is the fact that the missing primarchs are covered up. If they were known and liked by their brothers, they were obviously willing to do their part for mankind, so it seems contradictory of a hero-exalting society like the Imperium to expunge all records of them after dying. Doing this could've had bigger implications for the other primarchs. They probably would have started to grow resentful and mutinous towards the Emperor, knowing that when they fall they would be stricken from all records and doomed to obscurity for their efforts. Had they been executed due to their gene seed, the surviving marines would never had been taken in by the Ultramarines, they would have been disbanded and disposed of entirely. On the other side of the coin, they might have been allowed to live but not allowed to make more marines, it would hardly have been the primarch's fault for having poor gene seed, and disposing of a primarch is such a waste of resources, work, and potential. With their superior minds, they could have easily served as attendants to the Emperor and helped him with his work, or be diverted to tasks not involving leading a legion. Not to mention the Emperor was upset when he had to fight Horus, so killing a primarch might have actually been unthinkable to him. Tl;dr: based on my personal assumptions, the missing primarchs could not have been traitors, went undiscovered, or destroyed by the Emperor. Something truly strange happened to them. My personal opinion is that one could have taken his own life due to some shame he brought upon himself and his legion (or perhaps, losing his legion), and the Emperor, knowing this, chose to cover his son's shame post-mortemly. The other I think might have been too soft to be a primarch and wanted to live a normal life, and the Emperor, seeing a perfectly engineered super warrior desire nothing more than to be an unremarkable man, was so deeply touched by this raw display of humanity, he decided that his son's image, name, and history was removed to allow him to live in peace. Pretty noblebright for 40k, but 40k was pretty noblebright before the Horus Heresy.

[@MrWildcat28]

My 2nd Legion Primarch is stuck in the warp. He will finally appear out of the warp around the time Cadia “fell” with a large portion of his legion.

[@EidolonSpecus]

Note that they are usually mentioned as "traitors", not "heretics". It's possible that they did not fall to chaos like Horus' followers; but rather that they commited an even greater sin in the eyes of the Emperor: *_anti-imperialism._* The two lost primarchs may have been the punks/hippies of the family.

[@scragglefoot2179]

i always liked the theory that one of them landed on a world run by orks and became the most powerful digganob ever! then the emp found him but the digganob found it impossible to let go of his orkyness, this infected his legion with the orky spirit that ment they were unwilling to follow the emps rules and refused to learn about strategy this led to them getting wiped out during the crusades

[@Kay_Drechsler]

I was always in the opinion that these two chapters were just created to give players a chance to create their own chapters which participated in the great crusade and Horus heresy times. I do like all the other theories as well though. Great video of yours again!

[@namename3913]

The emperor himself wiped out one of the legions and completely avoided all contact with the primarch, because even Emperor himself fears Sly Marbo.

[@AriaLunaCampbell]

I think the answer I most prefer is a bit of a combination, although which answer applies to which is entirely guess work. That one and their legion died and was lost in battle, thus the lost, and the other and their legion exterminated for having some sort of flaw that was too great to ignore and made them not just a failure but, potentially, a possible threat even if they had not actively revolted or rebelled, thus the purged. That, at least, makes the most sense to me given the nomenclature used to refer to them and their legions. It would even go a long way towards explaining the differing ways the other primarchs refer to and respond to their absence. Guilliman yet keeping their places at the table even knowing they shall never return reads as a form of mourning and honoring the dead, of brothers lost tragically. Sanguinius reacts with fear of becoming like one of those legions due to the red thirst having seen firsthand what can happen if a legion is shown to have a flaw that is seen as a liability and even a threat by the emperor. Each primarch in their own way is marked by the tragedy and, honestly, I think that lends a much needed gravity and weight to their absence. A burden sitting on the shoulders of all remaining primarchs, reminding them that even they too could fail in battle, dying and being lost with their legion, or that they as well could bare some unseen taint, a malignancy that could see them put down like rabid dogs. Perhaps, even, such events helped plant the seeds that would leave some open to doubt and distrust in the emperor and their brothers. But, well, at risk of maybe getting too hypothetical and sounding sorta fanficky with all this speculation and, essentially, headcannon I'll leave it there. I just thought it worth sharing since, ultimately, I think half the fun sometimes with unanswered questions in lore is finding out how you and others answer those questions for yourselves. There's probably no real answer cause the mystery is, likely, half the intent and exists for us to do this sort of thing and I think that's pretty neat.

[@tedcook9621]

Given that some of the primarchs landed on some pretty horrible worlds and had awful experiences, Angron and kurze for example, it is possible that these two primarchs were found to be unsuitable by the emperor upon discovery in some such horrible way the emperor chose to simply abandon them to their fates. The legions they were supposed to have led simply got folded into the Ultramarines. Considering Angron's awful state when the emperor found him, It's quite possible he could have wound up a 3rd fallen or lost primarch. Curze is another candidate for being a failed primarch. Cursed with a form of precognition Curze was always a despairing figure driven slowly insane by seeing a horrible fate he felt he could not change.

[@NetMoverSitan]

1:33 - That was definitely Sanguinius kneeling before the Emperor, the wings are a giveaway. | 10:00 - The return of Big Papa Ultrasmurf. | Even the traitor primarchs weren't removed from all records and they almost destroyed the Imperium of Man, so the two lost primarchs either did something so bad that they didn't want ANY record of it or they had at least one gene-seed flaw which was too dangerous to even know about.

[@nathanlake898]

The 2 lost Primarchs became Alpharius and Omegon , Alpharius is the purged he is an outsider even amongst his brothers and no one in the imperium really knows Omegon even exists so he is the forgotten. Something happened with them and the emperor decided to re mold them into faceless men that could do all the sneaky unscrupulous stuff that the rest of the primarchs can't.

[@Ash828_]

One was purged at least 40 years before the Horus heresy in the book First Heretic Argel Tal kinda talks about it when he is in the gene labs looking at one of them

[@_lime.]

Wait, is there ever mention of the legions themselves being killed/destroyed? What if, simply, they were dead upon the Emperor's arrival and their legions were folded into the others? Maybe the Emperor didn't want it to be known that the Primarchs could die so easily and thus he expunged the records? Though i must admit, the idea that Reboute knew them and then had their marines added to his legion makes a lot of sense when you add to it the quote from Gulliman about keeping their places at his table do to "Honor". He may feel compelled to remember them because they were close friends or because some of their geneseed still exists within his legion.

[@lewa705]

What if both legions and their primarchs were set into stasis as a failsafe by the Emperor? He wiped all memory of them and basically made the galaxy forget about them, the best way to hide the ace up your sleeve is if no one is expecting it.