Board Thread:Warhammer 40k General Discussion/@comment-71.91.63.134-20150920063835/@comment-8881468-20151016131711

we must not forget that the heresy actually was responsible for a shitload of knowledge lost when the legions and mechanicumj fought amongst themselves.

I mean really< they had the tech to supply tons of terminator armors and all them old tranks.. the superheavies were a common sight.

@ the wikia contributor with the ultramarines: hotly contested as material from a big variety of books and least of them guilliman himself (in unremembered empire), state that mixing of legions has not happened.