Quote Originally Posted by Furious Mental
"plus like others have siad a knight wont give up his horse!"

Yes he would if the general who ordered it was influential enough.
That would actually be a nice touch, if a low influence, low command general would be unable to dismount his arrogant knights before a battle. The exception would be situations where it doesn't make much sense at all to fight mounted, such as defending from a castle assault or the aforementioned swampy terrain.