Units at Gettysburg on both sides were typically members of one of four branches: Infantry, Cavalry, Artillery, and Engineers. There were also other support units at Gettysburg, including provost guards, medical staff, and signal corps. This page explains a little bit about these branches.
Infantry. Infantrymen are land based foot soldiers, and they made up the vast majority of the units at Gettysburg. The typical infantry regiment consisted of 10 companies (each with exactly 100 men, according to Hardee’s 1855 Infantry manual, and led by a captain, with two lieutenants). Individual regiments (usually three to five, although the number varied) were organized and grouped into a larger body called a brigade. Infantry soldiers on the Union side used the insignia of a bugle, and the color for the infantry branch on both sides was light blue. Both armies organized their infantry similarly and the next section of this part of the site, understanding the order of battle, will explain that organizational system in detail.
Cavalry. Cavalry are forces that fought principally on horseback, armed with carbines, pistols, and especially sabers. As with infantry, cavalry were organized into regiments. In both armies, the cavalry was always accompanied by its own batteries or battalions of artillery (called “horse artillery”), as well as its own train of ammunition and supply wagons. Cavalry troopers wore yellow trim on their uniforms and crossed sabers were used as the main form of insignia.
Artillery. Both armies were equipped with field artillery. The basic unit of Union artillery was the battery, which usually consisted of six guns, almost always of the same type. Each gun, or “piece”, was operated by a gun crew of eight, plus four additional men to handle the horses and equipment. Two guns operating under the control of a lieutenant were known as a “section”. The battery of six guns was commanded by a captain. Confederate batteries usually consisted of four guns and were often of mixed type. Artillerymen on both sides wore red trimmed uniforms and used crossed cannon barrels as their insignia.
Engineers. A very small branch, both armies used engineers to build bridges and other roads. The Union army at Gettysburg had a volunteer engineer regiment from New York and a U.S. Regular battalion.
Medical. Both armies had a medical branch that consisted of doctors, nurses, and orderlies.
Sharpshooters. The Army of the Potomac had two sharpshooter, or “sniper,” regiments, the 1st United States and the 2nd United States. Champion marksman Hiram C. Berdan of New York was authorized in 1861 to raise a regiment of sharpshooters for Federal service. Qualified recruits had to place ten shots in a 10-inch circle at 200 yards, firing any rifle they chose from any position they preferred. Berdan organized companies in New York, New Hampshire, Vermont, Michigan, and Wisconsin. In the fall of 1861, Berdan organized a second regiment, with the men coming from New Hampshire, Maine, Pennsylvania, Michigan, Minnesota, and Vermont. Although officially members of the Third Corps, these companies were doled out and fought in different locations on the battlefield.
The Confederates did not have an organized sharpshooter regiment at Gettysburg; however, the South also made use of sharpshooters as well.
Provost Marshal and Provost Guard. These were essentially the military police of the Army, and their main job was to guard prisoners.
Signal Corps. The Signal Corps accomplished tactical and strategic communications for the warring armies. Flags (“wig-wagging”) were used to communicate messages across the battlefield. The Union Army had an organized signal corps, whereas the Confederate Army used a more informal system. In both armies, a signal officer was authorized for the staff at each corps and division. The chief signal officer of the Army of the Potomac at Gettysburg was Captain Lemuel B. Norton.
The next section of the site explains the order of battle, or how the armies at Gettysburg were actually organized.