All I can say is even though it's early access, it's one of the most polished games out of early access I've ever played. Created by the darthmod team, this game gives you the chance to start as a division commander work your way up through the ranks. No building railroads, recruiting spies or any of that extra shit. Just battles. Lots of battles. Ranging from the historic to minor engagements.
Right now, they only have the war up to the Battle of Antietam. The entire war is on it's way through updates.
I don't post here often anymore... but I can honestly say this might just be one of the best strategy games I've played in a very long time.
http://store.steampowered.com/app/502520/