Cossacks 2! I genuinely don't understand how this gem of a game doesn't have a not so large but extremely hardcore community that fixes all the bugs and QoL with mods. Now I haven't really played any other RTS games within the Napoleonic setting, but from what I've seen this one easily takes the cake in terms of historical accuracy.

Even though it has quite a few aforementioned bugs and the economy management system mostly focuses on capturing nearby villages for raw resources, I implore all history nerds to play this shit and bring it to life. Morale, fatigue from extended marching, effective range of fire, troop variety, different formations give different bonuses etc. But also the little things like the trees and hills giving cover and range bonuses, being able to capture enemy cannon, troops marching faster on roads and even troops being demoralized if a formation is broken near them.

Although this depth is absolutely amazing for a game that's literally 20 years old, it's probably the reason why the game isn't as popular as it rightfully should be.

E: Also, be aware that if you do play it, it might not work on windows 11 or 10. Strangely enough it runs well on over wine for me.