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
In 1975, Don Lowry released a set of rules called Grand Army. Designed for 9mm !? and 15mm figures, it allows players to recreate large scale battles for Napoleonics and the American Civil War. Grand Army now is available online.
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.
Honey Springs is a free, traditional hex-and-counter board game of the largest Civil War battle in the Indian Nations.