Board Thread:Warhammer 40k General Discussion/@comment-108.31.46.183-20150529014005/@comment-6078851-20150529155931

a martyr isn't necassarily religious: though the word itself was born, and used for a long time in a religous context, nowadays a martyr can just be someone who dies for a noble/popular cause, or a personal belief (which doesn't need to be a religous belief).

he probably got a lot of use from them post-liquidation - the thunder warriors were proto-astartes so he probably went back to work on their genome to improve, adapt, and add to what were obviously successful traits, eventually leading to his creation of primarchs and astartes.