A Civil War army consisted of many small parts that were joined together in stair-step fashion to make larger units. There were six basic units of organization. The smallest was a company, which had around 100 men. The largest was an army, which could have many thousands of men.
A company was the basic unit in a Civil War army.
A company had approximately 100 men and was commanded by a captain.
Companies were named with the letters A–K
(J was not used because it looked too much like I.)
A regiment usually contained ten companies.
A regiment had approximately 1,000 men and was commanded by a colonel.
If the unit had only four to eight companies, it was called a battalion rather than a regiment.
A brigade contained an average of four regiments.
A brigade had approximately 4,000 men and was commanded by a brigadier general.
Union brigades were named with numbers, but Confederate brigades were often named after their current or former commanding officers.
A division contained three to five brigades.
A division had approximately 12,000 men and was commanded by a major general.
Confederate divisions tended to contain more brigades than their Union counterparts. Confederate divisions often had twice as many men as Union divisions had.
A corps contained an average of three divisions.
A corps had approximately 36,000 men and was commanded by a major general (Union) or a lieutenant general (Confederate).
An army comprised from one to eight corps.
An army was commanded by a general.
The Union often named its armies after rivers or waterways, i.e., Army of the Potomac. The Confederacy named its armies after states or regions, i.e., Army of Northern Virginia.
Rank and Responsibilities
The rank of a Civil War soldier indicated his duties and responsibilities within the army. The vast majority of soldiers were enlisted men—they made up the bulk of the fighting force. Above them were noncommissioned officers (also considered enlisted soldiers) and commissioned officers. While officers had more prestige than privates, they also carried added burdens, since they were accountable for all the soldiers under their command.
A major general had the command and administrative responsibilities for an infantry division. He had to ensure that his division was well cared for and ready to fight when needed. In battle, he commanded his division by issuing orders to his brigade commanders on where to position their troops.
A brigadier general had the command and administrative duties for an infantry or cavalry brigade, made up usually of four regiments. He had to keep his men in good condition and ready to fight. In battle, he led his brigade by instructing his regiments on where to fight.
A colonel had the command and administrative duties for an infantry, cavalry, or artillery regiment, made up of varying numbers of companies. The colonel was expected to lead his regiment into battle personally to ensure that it performed to its utmost ability. For this reason, colonels were often killed or wounded in action.
A lieutenant colonel was the second in command of an infantry, cavalry, or artillery regiment. He had to assist the colonel in all duties, and in battle, he helped lead the regiment into the fight. If the colonel was killed or wounded, the lieutenant colonel immediately took command of the regiment.
A major was third in command of an infantry, cavalry, or artillery regiment and assisted the colonel in administrative and combat duties. In battle, an infantry major led the regimental attack, positioning himself at the front with the color guard. If the colonel and the lieutenant colonel were killed or wounded, the major took command of the regiment.
A captain had command of a company of infantry or cavalry, or an artillery battery of guns. In addition to his administrative duties, an infantry captain led his company into battle by giving the proper commands for the movement and fighting of his troops, in concert with the other companies in the regiment.
Lieutenants were second in command of infantry and cavalry companies and artillery batteries. Infantry lieutenants assisted the company captain in their positions behind the line of battle by guiding the troops in their movements and firing.
A sergeant major was a regimental staff member responsible for keeping reports for the regiment. In battle, he advanced on the left, behind the line of battle, to help guide troop movement.
Sergeants served either in the regimental color guard or in the individual companies of the regiment. There could be divisions, related to administrative duties, within the rank—for example, first sergeant, ordnance sergeant, and quartermaster sergeant.
Infantry sergeants advanced either in or behind the line of battle, depending on individual responsibilities. They helped guide troop movements and kept the men in their positions by example and force of command.
Corporals served either in the regimental color guard or in the individual companies of the regiment. During combat, infantry corporals who were not part of the color guard were positioned in the line of battle. They helped to keep a uniform line in the movement of the company. Privates looked to corporals to help guide them during combat.
Privates served as the backbone of the army and did most of the fighting in battle. Privates moved together shoulder to shoulder in straight battle lines and acted on the commands of their company officers. Privates rarely acted independently but rather worked as a group with the single purpose of fighting as a sheer force of numbers.
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In addition to the regular ranks, Civil War armies had several specialist ranks.
Each regiment had a contingent of staff officers, which included surgeons, quartermasters, adjutants, and, on occasion, chaplains.
There were also special ranks for soldiers in specific parts of a regiment, such as the
field music (fife and drums),
the regimental band (brass instruments and drums),
and the color guard.
The color guard was an honorary group chosen to carry the flag, or colors, of the regiment. It usually consisted of eight color corporals and one color sergeant.