Board Thread:Warhammer 40k General Discussion/@comment-6078851-20130130174042/@comment-5880884-20130219102741

Primarchs are not designed to age and die after the Great Crusade. In the Horus heresy novels it is revealed to us that the emperor built living quarters for the primarches on terra to give his primarchs a place to retire to after the great crusade ends.