Having only just attended the Black Library Live event and with the Horus Heresy weekender just round the corner, I was hoping to talk about what is probably the biggest unanswered question in the Horus Heresy. That is of course about the two unknown Primarchs which are numbers 2 and 11. I would first like to worn you that there maybe some spoilers, however, those of you who have read the Horus Heresy novels will know that any time where the two missing Primarchs are mentioned, it is normally just in one sentence, so the possible spoilers here are not exactly ground breaking.
So I would like to go through so parts where they are brought up in the novels and give my thoughts on what they could mean. Please note that I am not fully up to date with the novels and there is a high chance that I have missed little hints here and there because as I said earlier, they are normally brushed over very quickly.
So firstly I wanted to talk about a few parts in the novel, The First Heretic as this is probably the earliest, chronological story. At one point, Lorgar states he fears the "Emperor will break the Word Bearers - and break me. We would be cast alongside the brothers we no longer speak of."
This clearly shows that these two Primarchs where cast out at some point after they were discovered on there he wold , and before the events on Monarchia which was 43 years before Isstvan 5.
In this novel, it also mentions that around the time that the 2nd and 11th Legions were expunged from Imperial records, the Ultramarines Legion swelled in Astartes numbers to eclipse all other Legions.
If this were true, it would suggest that the legionnaires of the 2nd and/or the 11th haven't committed any offence and that the "crime" lies with the primarch, and possibly a minority of the legion.
During the vision of the Gal Vorbak, the 11th Primarch is described as still being innocent and pure before the disaster that scattered the Primarchs. This also suggests that whatever the 11th Primarch done to make him cast was after he was discovered on the planner he was raised on. One of the Gal Vorbak also says that killing the 11th Primarch in the past would, "save them a lot of trouble", which could be interpreted as saying the Word Bearers had some connection with "dealing" with the legion.
The next novel I would like to bring up is Prospero Burns. At a point leading up to the Wolves attack on Prospero, Leman Russ Was asked if he was concerned over the fact that Space Marines were fighting other Space Marines. To this, he commented that this was not the first time the Wolves had been called on to perform this task. This might be a reference to whatever happened to the 2nd and/or 11th Legion, especially as the wolves stated earlier one in the novel that Leman Russ was created to be the Emperor's executioner. However, Leman Russ could be referring to other conflicts that he has had with other Legions
Last on my list is in The Outcast Dead. During a conversation regarding what could happen as a result of Magnus using forbidden powers to contact the Emperor, he states that the "Wolves will be loosed again". This not only further implies that the Space Wolves were involved in what happened to the 2nd and/or 11th, but it also shows that people out side of the space marines are aware of what happened with the two unknown Primarchs.
Now as I said previously, I'm sure that I have missed some other hints as to what happened the the unknown Primarchs, but feel free to comment below. However, to summarise, we know that the incident with the two Primarchs happened at some point between them being found on the planets that they were raised on, and around 46 years prior to the Horus Heresy. We are also led to believe that the Space Wolves and the Word Bearers were somehow involved in whatever happened to them. Anything other than that, unfortunately we are not able to confirm. We are not even able to confirm wether is was two separate incidents or just one incident involving both the Primarchs. I just really hope that Black Library do cover exactly what happened and not just dismiss it whenever it is brought up, but we can all hope :-)
Please comment below as I would love to read your thoughts and possible theory's that you have.