Lost legions

the other two...that is a conversation for another day Emperor talking about the lost primarchs to Corvus Corax

who were they??

The Emperor created the primarchs, this is not news, its fact, these primarchs became the leaders/generals/badasses of the imperium. they lead the space marines and they kick xeno/daemon ass across the galaxy, all of this is known to the fans of whom should be reading this. However a mystery has always clouded over the imperium and one that no one reallhy has an answer to, and that is the lost legions. whilst there are meant to be 20 primarchs with each respected legion, there are only 18 recorded pretty much everywhere you look, no matter how hard you look you can only find hints and references to these lost two. in the current continuity of 41k there is no 2nd or 11th legion, all imperial records have been expunged from every archive/data base/media outlet across the imperium. Except there are a few facts here and there that can be dound either as quotes or hints but no solid proof, for instance Big-E himself of course obvviously knows whats happened as he makes a quote about them to corvus when they first meet, its also stated that most if not all the 18 primarchs and some adeptus astartes and custodies actually know the fate of these lost two, this means that its common knowledge amoungst the elders of the imperium yet it is never spoken of directly and only ever subtely hinted at.

why they a thing??

GW however have stated that this obsucrity is on purpose as to allow the fans to creat their own legion and make them either chaos or loyal, to add to the creative element to the fluff, for example the Angry Marines is said to be the lost 11th and the Pretty Marines to be the second.

what happened to them??

As of now there is no offical answer to that but that dosent stop the neckbeards from coming together to theorise the shit out of this. As for now all the information we have is this. it was either the inquisition that was responsible for the expunging of the archives and pride themselves on its succsess (cocky pricks). Both legions were banished for what must have been a good reason, either a genetic defect or impurity in the gene-seed, or an act of unspeakable HERESY to the imperium that the only reasonable punishment was Exterminatus. the chances are and the most likely conclusion is that one way or another, the Space Wolves were involved, probably earning them the title of executioners. After the event of which resulted in the expunging of imperial records, it was rumoured that the Ultramarines combat effective numbers skyrocketed eclipsing all other chapters in number and becoing the bulk of the imperium, whether this is just speculation or true is unconfirmed.

first ever edit to 1d4chan this is my first ever addition to this site, feel free to correct or add anything or change mistakes i honestly dont mind, if im wrong about anything please feel free to correct me and thanks for reading