Board Thread:Warhammer 40k General Discussion/@comment-26331252-20151005162829/@comment-26420219-20170427213109

@ 217.46.104.208 That is true but only since the publishing of Praetorian of Dorn. Before that (in the late 90s and earl 2000) the canon-material stated that Alpharius was supposedly killed at the Battle of Eskrador. It was only through the Horus Heresy novels that the idea of the twin-Primarch Alpharius-Omegon was introduced to the Warhammer 40k universe. As Omegon takes on the mantle of Alpharius, we could assume that he was the one slain at the Battle of Eskrador, although we can’t know for sure as GW continually rewrites and expands on the existing lore.

At the moment the Battle of Eskrador is still canon, but this could change in future.