How would the discipline training and effectiveness of battlefield discipline differ between the medieval period and modern day soldiers? Was there any kind of 'breaking down' training done in the medieval period?(I read about Templar being forced to spit on their crosses to show them what it would be like if captured, was this type of training common?)
I know it's a really broad question, so to narrow somewhat; how would a the discipline standards differ from an average English man-at-arms in the campaign before Crecy differ from an average American infantryman in Iraq?
Frankly, there's no (useful) way to compare the two. Medieval armies did not have the kind of centralization and structural cohesiveness that would allow us to establish a baseline for comparison. While most combatants on the typical medieval battlefield would have trained for war to greater or lesser degree, there were no medieval boot camps and certainly no medieval Pentagons. The behavior and conduct of modern soldiers is governed by an enormous number of laws, rules, regulations, many (if not most) of which would be alien to the medieval warrior and the medieval world in general.