Diffrent periods.
The easiest would be Seven years war, a lot of uniforms to change, but only a little codeing to change the way the battles are fought.
Then you have the American War of Independence, to do that you would first and formost need to change from 1:10 to 1:1 figure scales as the battles are so small.
Most units were only 200-400 soldiers, and you had much fewer units to, the biggest battles of the war was 30 000 strong, something the game can easly handle. and most were less then 15 000.
After that you have War of spanish succesion, here you have to change quite alot, in coding to change gameplay, but the uniforms are simple, most used the same type.
The realy had ones to do would be Great Northen war and 30 years war. here you have pikemen, and I'm not sure it's even possible to code that into the game, here to you could have 1:1 scale as most battles were less then 50 0000 soldiers