Board Thread:Warhammer 40k General Discussion/@comment-69.143.134.163-20150419161351/@comment-62.44.135.213-20160701094056

There is or was only one lost primarch. The emperor if he realy created 20, then the twins most count as two. So 10 rebelled, 9 stayed true to the emperor. And only one is lost. Unless the emperor hid from everyone that he actually created 21.