The Wooden Horse: I think, seeing this about 10 years ago, it must have been one of the first black & white films I saw, sat all the way through, and thoroughly enjoyed. My memory of it is hazy, but I would tentatively place it above The Great Escape (a film you get really sick of hearing about, growing up in Britain.)
Also, No Man's Land ( more of a play than a film, it's worth checking out) and Waterloo (epic battles scenes still look fabulous; reminds me of Barry Lyndon) and Millions Like Us (Powell & Pressburger were not the only ones making excellent propaganda films!)
I would, like Winrit, like to hear some medieval suggestions.