[quote=KabenSaal]
The soldiers I have planned are guerilla bow-wielding ambushers. Not very good in the open field. Very good in your camp, poisoning your food, water, reserves, and blowing up your gunpowder stores.
[/quote]

Defense-oriented army will put an end to your slipping in!
Because most of the time, you won't find them outside a town or city. If you do find them, there's an airship overhead.