[@UltikanaRe] Strategy, weather, element of surprise (or lack thereof), traitors... Sure, this can be reduced significantly with good planning, adaptability, discipline, etc., but imo it won't be as easy as you may think.

I get what you're saying, and agree with the fact that the largest, strongest army will always succeed. Size of the army is generally going to increase as the amount of land you control increases, so adding the # of tiles approximates this. Strength of the army isn't as easy - beyond allocating additional modifiers to the construction of barracks, siege equipment, training sessions, etc. (all of which I definitely feel are reasonable, and are perfectly okay with me as long as the values are reasonable. They aren't mentioned in the OP, but it [i]is[/i] mentioned somewhere IIRC that I am lenient about creative stuff like this as long as it is reasonable. If this is not mentioned, then I will add it), there isn't much more that can be done. There is already a modifier for battling more than once within a short period of time, representing fatigue, homesickness, etc.