Military Organization: Both North and South used the old English organization of their armies. The company  was the smallest unit commanded by an officer, usually a lieutenant, or preferably, a captain. It contained about 100 men when formed, and was designated by a letter(A, B, C, D, E, F, G, H, I, K-note no J), there usually being 10 to a regiment, although sometimes artillery and cavalry regiments had more than 10. Each company was designed to be subdivided into 4 squads, each being led by a corporal or sergeant. Prior to the Civil war, volunteer regiments were usually named for their commander, who often was the person who raised the unit (e.g. Fox's Regiment). This was used during the war also, but the Dept. of the Army had previously started requiring the states to number their regiments in the categories Infantry, Cavalry, and Artillery. Regiments were usually commanded by a colonel. There were usually 5 regiments to a brigade, commanded by a brigadier general , 3 brigades to a division, and 3 divisions to a corps. Early in the war, there were many political appointees leading regiments and brigades. As the war went on, although many units were decimated by disease and battle, the new recruits were often formed into new units, making all the units above very uneven in strength and command.

Parole: Lacking the means for dealing with large numbers of captured troops early in the war, both North and South relied on the traditional European system of parole and exchange of prisoners. The terms called for prisoners to give their word not to take up arms against their captors until they were formally exchanged for an enemy captive of equal rank.  Parolees were directed to a specific location(sometimes their home!) to await exchange, which often took several weeks or months.  When this system proved ineffective, both sides started imprisoning the captured soldiers and only a few were exchanged.