Board Thread:Warhammer 40k General Discussion/@comment-6767898-20130227013545/@comment-6078851-20130331152842

Sindri Myr wrote: Absolutely Silverman, & personally, I bet Roboute Guilliman would be pretty ashamed of the Chapter & all its successors for allowing themselves to become so conceited & having effectively prohibited indepandant thought. Although it doesn't look like it on the outside, he DID appreciate independant thought & original thinking, at least in a few cases. After all, he rewarded Sergeant Thiel for his different tactics, which helped to win the battle of Calth.

i read on this wiki about marneus calgar declaring a death oath upon uriel ventris for original thinking that won a battle against tyranids. 'dereliction of duty' i think was the term used for his actions because he didn't comply with the codex astartes.

i'm not clued up on the whole event however so i may be missing salient information, but it seems to me that  marneus is maybe more concerned with following the codex astartes to a fault, even if it leads to bad situations, rather than use non-codex compliant tactics - even if they work.