Military Organization

During the war, states and territories, and parts thereof, were divided into military divisions, departments, and districts, each under military command.   These were added, changed and eliminated frequently to meet existing political and military requirements.   For example, the District of Columbia was in the following departments during the war: Department of the East from January 1, 1861 to April 9, 1861; Department of Washington to August 17, 1861; Department of the Potomac to April 4, 1862; Department of the Rappahannock to June 26, 1862; Military District of Washington to September 2, 1862; Defenses of Washington to February 2, 1863; and Department of Washington to the end of the war. ^{Phisterer 24,29}   Each department was under the command of a military unit, usually a corps or an army, which are discussed below.

(See Navy Organization below.)

An army is the largest operational organization of land forces.   An army is associated with a geographical area called a department.   Corps are aggregated into armies. There were at least 16 Union armies and 23 Confederate armies during the war.   Armies are commanded by major generals in the Union and, usually, by full generals in the Confederacy.   Corps and armies usually have some artillery and cavalry attached.   Each army has a number of staff officers. The organization of an army is as follows: 10 companies = 1 regiment = 1 battalion, 3 to 6 regiments = 1 brigade, 3 to 6 brigades = 1 division, 2 to 4 divisions = 1 corps, 1 to 3 corps = 1 army.   Each of these units is organized as follows for infantry, artillery and cavalry:

INFANTRY:

Company

The lowest unit in the army is the company with a maximum strength of 101 officers and men commanded by a captain.   Commissioned officers are a captain, 1st lt., and 2nd lt.   Non-commissioned officers are 1 1st sgt., 4 sgts., and 8 cpls.   1 company = 2 platoons = 4 sections = 8 squads.   When divided into platoons, the captain and 1st lt. command each platoon.   Enlisted men are 82 privates, 2 musicians dnd 1 wagoner. ^{Fox 5}

Regiment and Battalion

Commissioned officers are a colonel, who commands the regiment or battalion, a lt. colonel, major, adjutant (1st lt.), surgeon (maj.), 2 asst. surgeons (capt.), quartermaster (lt.), chaplain, sgt.-major, quartermaster sgt, commissary sgt., hospital steward, 2 musicians.   A regiment has 10 companies for a maximum total of 1025 men, while a battalion has 4 to 8 companies and is usually commanded by a major or lt. colonel. ^{Fox 5}   A regiment in the regular army (not the volunteer regiment) could also be composed of 16 companies of about 1,630 men.   During operations, these maximum strengths never existed because of casualties, illnesses, absences, desertions, etc.   The actual fighting strength of a typical regiment was from 650 to 710 men. ^{Phisterer 63}   Regiments were divided into 2 battalions of 8 companies each.   There were few regular army infantry regiments in the Civil War.   Most infantry regiments, 2,144 in Union armies and 642 in the Confederacy, were volunteer and raised in the the same state area, so they became the soldier's "home away from home" with considerable emotional attachment.   They were the basic fighting units of the Civil War and many have legendary histories.

Brigade

A brigade is composed of 3 to 6 regiments commanded by a brigadier general with staff.   Artillery units might be attached.

Division

A division is is composed of brigades commanded by a major general with staff.   In the Union, the division size is usually 3 or 4 brigades, but in the Confederacy, it is usually 4 to 6. Therefore, a Confederate division tends to be almost twice as large as a Union one.   Artillery battalions were attached and, occasionally, cavalry units might be attached.

Corps

A corps is is composed of 2 to 4 divisions commanded by a major general in the Union or a lieutenant general in the Confederacy.   Each corps commander has staff officers.   Attached were about 9 light artillery batteries.   Corps did not exist in the armies early in the war.

CAVALRY

Company or Troop

The basic unit is the troop or company, organized pretty much the same way as an infantry company with a theoretical strength of 100.   When the troop dismounted for battle, 1 man in 4 stayed behind to guard the horses.

Regiment and Battalion

As in the infantry, the commander was typically a colonel.   The Confederate regiment was composed of a 10 troops, headed by a captain and assisted by 1st and 2nd lieutenants.   A regiment in the Union volunteers consisted of 12 troops.   In the Union regulars, 2 troops form a squadron, 2 squadrons form a battalion, and 3 battalions form a regiment.   Battalions consisted of 4-8 companies.   There were 272 Union cavalry and 137 Confederate regiments in the war.

Brigade, Division, Corps

These were organized like the infantry.

(LIGHT) ARTILLERY

Battery

The basic unit of artillery is the battery, which has 4 to 6 guns, is commanded by a captain, assisted by 4 lieutenants, 2 staff sergeants, 6 sergeants, 12 corporals, 6 artificers & farriers (blacksmiths), 2 buglers, 52 drivers and 70 cannoneers for a total of 155 men.   It typically has 4 guns in the Confederacy and 6 guns in the Union.   A battery is a subdivided into gun crews of 20 men and into sections of 2 gun crews, 2 or 3 sections per battery.   A gun crew is commanded by a sergeant and a section by a lieutenant.   Each gun is attached to a limber, which is a 2-wheel ammunition chest drawn by 3 pairs of horses in tandem, called lead, swing and wheel pairs.   Each gun is supplied with 6 or more caissons, which are mounted on 2-wheel carts containing 2 or 3 ammunition chests.   The caissons dnd limbers could be connected together (note the extra wheel and connecting rod below the caisson) during travel.   A traveling forge accompanied the battery.   There were 432 Union and 227 batteries during the war. ^{Faust 45}

Battalion (Confederacy) or Brigade (Union)

The battalion or brigade contained 3 or 5 batteries of artillery commanded by a colonel, lieutenant colonel, or major.   There were 72 Union brigades and 16 Confederate battalions in the war.

Artillery Reserve

Each infantry division usually has an artillery battalion, and each corps or army has a reserve of 2 to 5 artillery battalions.   Each division's artillery usually fights alongside the infantry, and the artillery reserve is a mass of about 5 brigades, of 21 batteries.   The artillery reserve is commanded by a brigadier general or colonel.

Heavy Artillery

The Union organized some "heavy artillery" regiments containing 12 artillery batteries of 150, or 1800 total trained both as infantry and artillerists.   They were organized in much the same way as infantry regiments, but were larger to provide enough men to man the guns.   These originally defended Washington, but in 1864 they joined Lt. Gen. Grant's army, where they served more as infantry.   There were 61 heavy artillery regiments in the war.

ENGINEER

Engineering regiments were raised to build forts, entrenchments, bridges, and other military construction.   They could fight when called on, but usually work on construction, even under fire.   There were 13 engineering regiments during the war.

SHARPSHOOTER

The Confederate sharpshooters were usually independent companies, but the Union raised two sharpshooter regiments, Berdan's 1st and 2nd US Sharpshooters.   These regiments are organized as infantry.   Usually they are assigned to skirmish duty, or they roam around the battlefield to find good positions from which to shoot at enemy officers in the rear.

The Union Armies

The Confederate Armies