The german version of the Wikipedia article about the
battle of Kadesh says that one of Ramses II major mistakes was to have the divisons of his army marching 10km apart from each other and states that this meant a whole day of marching at that time, thus preventing the latter divions (who were just marching along the path of the previous devision) to reach the battle!!! The army consisted of 4 mixed divisions, each counting 5000 men. Well, you never know about wikipedia's truth, but I believe that one so far...
One should also consider that heavy rain, snowfall, etc. might furthermore prohibit marching at all!
Then I think there was a delay due to wait for short-range scouting: Where can the army pass? Where are suitable places for the night? Could there be places for ambushes?
The lack of proper roads poses another problem: An army of 5000 cannot march like ducklings one after the other along a mere trail. So how do they cross smaller rivers (I suppose Dom2-Maps show only major rivers, but not smaller brooks which already present a problem in the absence of big bridges!) or hills??? I thought armies of those times were sometimes even required to breach their way through smaller forests, no?
I am not speaking of mountain or forest provinces, since I suppose that "plain"-terrain type entails terrain having some smaller woods, smaller rivers (floodplains), dales and hills, but not a real huge wild forest without any trails! Likewise I imagine mountain provinces to be like the alps. BTW, how long did it took Hannibal to cross the alps?
I am no military expert and neither am I a historian, but by the considerations above I doubt that a roman army could traverse the breadth of england or german in a single month. Thus I guess that this all severly limits the size of those provinces even further. Also, not all provinces are of the same size, so some are easier to traverse than others, despite having the same terrain modifier. Who is an experts for mediaeval warfare here?
