One of the ways I have my monument project organized is by the “Order of Battle.” Order of Battle refers to the way the armies were organized. This page will explain the basic organization of the Union Army of the Potomac and the Confederate Army of Northern Virginia.

The Army of the Potomac

The Army of the Potomac consisted of:

Seven Infantry Corps. The seven infantry corps in the Army of the Potomac at Gettysburg were the First, Second, Third, Fifth, Sixth, Eleventh, and Twelfth. These corps commanders, who were all major generals, answered to the overall Army commander, General Meade. (You can often identify what corps a unit was part of by looking at the monument and noting the corps badge elements included on many of them if you understand the corps badge system adopted by the Army of the Potomac.)

Each of these seven infantry corps consisted of at least two or three divisions. Divisions were numbered. The First, Second, Fifth, Sixth, and Eleventh Corps each had three divisions; the Third and Twelfth Corps each had two divisions. Division commanders, typically major generals or senior brigadier generals, answered to their corps commander.

Each division consisted of between two and four brigades, with three brigades being the most typical number. The First Division of the Second Corps was the only division to boast four brigades. Brigade commanders, typically brigadier generals or senior colonels, answered to their division commanders.

Finally, the basic unit was the regiment; typically three to five regiments made up a brigade.

Attached to each infantry corps was one brigade of artillery. This brigade answered to the corps commander and was typically commanded by a senior captain.

The Army of the Potomac also had a Cavalry Corps consisting of three divisions, with typically three brigades in each division. There were two brigades of Horse Artillery attached to the Cavalry Corps. These units were typically doled out to the division commanders.

In addition to the artillery who reported to the corps commander, the Army of the Potomac had an Artillery Reserve which had its own commander and answered to the Chief of Artillery. The Artillery Reserve of the Army of the Potomac consisted of four artillery brigades and a train guard.

Finally, the Army of the Potomac had various support troops attached to its headquarters; these soldiers generally answered directly to the Army commander. This included General Meade’s staff, the Provost Marshal (military police) brigade, a select group of guards and orderlies, and an engineer brigade.

The Army of Northern Virginia

The Army of Northern Virginia consisted of:

Three Infantry Corps. The three infantry corps in the Army of the Potomac at Gettysburg were the First, Second, and Third. These corps commanders, who were all lieutenant generals, answered to the overall Army commander, General Lee.

Each of these three infantry corps consisted of three divisions. Divisions were named after their commander. Division commanders, typically major generals or senior brigadier generals, answered to their corps commander.

Each division consisted of between three and five brigades, with five brigades being the most typical number. Brigade commanders, typically brigadier generals or senior colonels, answered to their division commanders.

Finally, the basic unit was the regiment; typically three to five regiments made up a brigade. In the Confederate Army, it was typical for a brigade to consist almost exclusively of troops from one state.

Each division had a battalion of artillery attached to it, and each corps had two artillery “reserve” battalions for use by the corps commander.

The Army of Northern Virginia had a Cavalry Division which directly reported to the army commander. This division consisted of six brigades and a battalion of horse artillery.

That gives you a basic overview of how the armies were organized at Gettysburg.