In such a case the simplest solution would be to look at BM's representation and find the closest historical parallel. There is no problem, only a required approximation.
In which part of Europe? For example Self economies sprung up late in the eastern part of Europe, and tended to persist past the time the institution was dismantled in western Europe. Some countries like Wales persisted with small "professional" armies with a emphasis on single melee combat while other realms had started to practise "conscription" of peasant levies and the use of formations required by larger forces.
In general combat was a fair bit simpler then we would perhaps suspect, since communication on the battlefield was somewhat difficult. Simple battle plans that could then be tweaked by the battlefield commanders as the situation changed gave maximum flexibility in this regard. Like the early phalanx combat of Greece, set piece battles were common.
This opinion is based on the Military History I learnt while training to be an army officer. We learnt tactics and strategies from many historical ages as a way to demonstrate how limitations of things like communication and logics dictates the available strategic options.
