Hardtack is a set of regimental Civil War rules based on the excellent Stargrunt II rules. With a scale of 1 fire = 3-5 men, it’s intended for fighting one regiment v another, filling the space between Johnny Reb and Brother v Brother.
The Jackson Gamers have a page with everything you need to know to start gaming Civil War Ironclads
Here are a set of house rules for “fine tuning” Fire and Fury, the great American Civil War rules set.
I’m not sure I’m on board with all of these.