What were the different types of army units such as regiments during the civil war?

Answer The major unit on the field of battle was an ARMY. This was divided into CORPS, usually 2 or 3. Each Corps consisted of 2 DIVISIONS. The Division was divided into 2 BRIGADES, which was the primary unit that maneuvered on the battle field. A Brigade consisted of 4 to 6 Infantry Regiments and a battery of Artillery. Cavalry was organized into Brigade but were usually assigned as Regiments to support an infantry Brigade. Originally, the infantry Regiment was about 1000 men in 10 COMPANIES. A Company was the basic unit that a soldier identified with. The Company was commanded by a Captain, whereas the Regiment was commanded by a Colonel. The Brigade was usually commanded by a General and this may be the origin of the rank "Brigadier General". As the war progressed, the regiments became smaller and it was not unusual to find less than 200 men in a Confederate Regiment. Some regiments became so decimated, that they merged or combined, thus the name 29th/30th Mississippi Regiment. Example of an Army Organization: Army of Mississippi (CSA) at Battle of Shiloh: http://members.aol.com/MissRegt/AOMShiloh.htm