The terms used to describe Civil War units can be confusing. This note is meant to help those new to military affairs grasp unit sizes and how units fit together.
The basic organization was the company. This was the soldier’s home, his wartime family. At the war’s outset, a company may have had one hundred or more soldiers. By the end of the war, some companies consisted of a half dozen men or simply ceased to exist. A company was supposed to be led by a captain, with lieutenants to assist him, but leadership casualties might result in companies commanded by a lieutenant or even a sergeant.
The regiment was the soldier’s extended family or clan. Asked to whom he belonged, a soldier would reply, “Sixty-first Georgia,” or, “Eleventh Vermont.” Regiments went to war with approximately eight hundred men. Some ended the war with fewer than a dozen survivors. A regiment was authorized a full colonel as its commander, but devastating casualties (especially late in the war) sometimes left a regiment under the command of a captain or even lieutenant.
The brigade united the regimental clans into a tribe. Strengths varied, but at the war’s outset the standard was between twenty-five hundred and three thousand men in four regiments. Due to attrition, by mid-1864 it wasn’t uncommon for a shrunken Federal brigade to contain five or six reduced-strength regiments, while some consolidated Confederate brigades included twice that number of severely battered regiments. Brigades were supposed to be commanded by brigadier generals (one star), but on the Federal side brigades frequently were commanded by colonels or even lieutenant colonels as field officers became casualties (promotions were more generous among the Confederates, and gray-clad officers from brigade through army levels generally held ranks one grade higher than their Northern counterparts).
Divisions consisted of two to three brigades (occasionally four or more in the Confederate States Army). A full-strength division fielded eight thousand to ten thousand soldiers, but by late 1864, divisions averaged between two thousand and five thousand men (Confederate divisions were fewer in number, but generally larger in size until the war’s closing months). A division was supposed to be commanded by a major general (two stars) and usually was in Confederate armies, but Union divisions most often were led by brigadier generals or, by 1864, even colonels.
A corps at full strength might have two, three, or more divisions, with an authorized strength of twenty-five thousand or higher. In the summer and autumn of 1864, when this account takes place, it was rare for a corps on either side to approach that number of troops present for duty. In the Confederacy, a corps was commanded by a lieutenant general (three stars). Among the Federals, a major general usually commanded a corps.
An army was, by doctrine, a force of two or more corps, but occasionally an independent maneuver force of two or three divisions was designated as an army. North and South, armies were given names based upon geographic features. The North preferred river names—the Army of the Potomac or Army of the Shenandoah—while the South employed regional names, such as the Army of Northern Virginia or the Army of the Valley. In the Confederacy, lieutenant generals or full generals (four stars) commanded armies. In the North, they were commanded by major generals. When given a third star, Ulysses S. Grant became the Union’s senior officer as a lieutenant general, while the South had a number of full generals. Armies varied widely in size, from well over a hundred thousand men to fewer than ten thousand, but the army remained the highest field organization on either side.
When the reader encounters the stand-alone term Army, thus capitalized, it refers to the Regular Army of the United States. By contrast, army is used when soldiers are referring to their own organizations.
Actual numbers of soldiers on any given battlefield can be infernally hard to determine, since records (especially among Confederates) could be spotty or were destroyed and because Yankees and Rebels counted men differently, with the Federals tallying each last cook, while the Confederates counted only those wielding weapons. Also, each side had different attitudes toward replenishing forces that had suffered casualties. Governors on both sides liked to create new regiments—allowing them to reward constituents with officers’ commissions—but the South was better about supplying individual replacements to veteran units, while the North continued to generate new regiments until late in the war. An important result was that even in 1864, a Confederate brigade or division might outnumber the Union brigade or division it faced, but the Union would bring to bear a greater number of brigades and divisions on the battlefield.
The cavalry generally was organized along the same lines as the infantry up through division. The term battalion applied to infantry or cavalry meant a unit about half the size of a regiment (a “demi-regiment”), or a regimental element deployed for a special purpose or tactic. While the formal maneuver battalion is the building block of today’s U.S. Army, it was an anomaly during our Civil War.
The artillery was organized into batteries of four guns in Confederate armies or six guns in Union formations. Batteries might be grouped into battalions, regiments, or even brigades, although the term regiment was most frequently used as a designator for “Regular Army” units in the North, so one might encounter Battery A of the 2nd U.S. Artillery.
Confused? Not as much as were the soldiers on those terrible battlefields.
(With special thanks to Brigadier General John W. Mountcastle, U.S. Army [Ret.], and Robert E. L. Krick for adjusting my fires.)