This list of formation types is designed to help beginning Republic players to relate real life army formations with those used for game play. The list indicates only very rudimentary averages, and players should remember that real life units varied quite a lot in both quality and size. At some points, "green" troops were well trained and could perform very impressively. In other cases, regular troops could become a bit cagey as their understanding of the true dangers were honed to a point. Unit descriptions include type and year, average brigade size (number of combat bases) and common troop grades. Note that unless otherwise indicated, the infantry formations listed are line infantry (as opposed to light infantry). The confederacy more commonly assigned individual light infantry (sharpshooter) battalions to line brigades. Such line brigades will use skirmish markers one grade better than that of the main member regiments (i.e., green markers becomes veteran, etc.).

The cavalry tables include a classification of cavalry types, with extra notes on whether the cavalry in question will dismount while in the proximity of the enemy, what their dismount ratio is and what the resulting dismounted combat base represents. The dismount ratio is the number of mounted bases that must be removed in order to create one dismounted base. A 1:1 ratio means that one mounted base is removed to create one dismounted base (usually medium cavalry). A 2:1 ratio means that it takes two mounted bases to create one dismounted base (usually mounted infantry). Cavalry armed with sabers, sidearms and shotguns (maybe some muzzle loading carbines) are considered to be a type which remains mounted under grand-tactical combat conditions. For the sake of game mechanics, this type of cavalry is referred to as Light Cavalry. Players with particular knowledge of cavalry operations should feel free to adjust these cavalry classifications as needed. Note that Union cavalry's reputation for being weak in 1861 was mostly related to the small number of regiments, their scattered deployment and lack of efficient high command. The Confederacy started the war with a more aggressive volunteer cavalry program that initially put greater numbers of larger experienced formations into the field.