I haven't played it yet but there is a CW scenario that shipped with Civ V Brave New World, looked very similar to the style of R.E. Lee CW General, which is another good game.
Link.
I've played the mods for both Empire and Napoleon as well, both of them are pretty but they aren't balanced very well.
That being said, the guy that created Darthmod is working on a Gettysburg RTS that should be ready within a year or so, and given his recent work with the Total War series it should be really good.
http://www.ultimategeneral.com/blog