The principal guns widely used in the field are listed in the following table.

Artillery played a crucial role in determining the outcome of the Battle of Gettysburg. (See Battle of Gettysburg and the Infantry, Cavalry, and Artillery.) Artillery units fought desperately side by side with their infantry counterparts during all three days of the battle and Union guns made up the difference during the July 3rd finale known as Pickett's Charge. Today, there are hundreds of cannon that line park avenues at locations where Union and Confederate batteries were established during the battle. Each position is marked by a tablet or monument with a compliment of cannon of the type used by that organization during the battle. Visitors are quick to note that the guns on both sides are very similar in design and made of bronze or iron. In fact, Confederate artillery units were not only armed with Southern-made cannon, but a number of captured Union guns filled Southern artillery organizations. One popular story relates that a captured Confederate soldier was observed closely inspecting the guns of a nearby Union battery. The man would look at the "US" stamped on the top of each gun barrel then simply nod his head in acknowledgement. When a Union soldier asked the Southerner what he was looking at, the man replied, "Ya'll have as many of them thar US guns as we have!"

Artillery in the 1800's fought side by side with infantry units because the range of the big guns limited them to visible targets. Like the infantry weapons, Civil War-era cannon were muzzle loaders and required a crew of eight men to aim, load, and fire the weapon. Maintaining the large guns was an important job and discipline in the artillery was very strict due to the value of the weapon. One artillery unit was referred to as a battery. Composed of six cannon and just over one hundred men, the battery was commanded by a captain. Many batteries were companies of an artillery regiment. Battery A, 4th US Artillery or Battery B, 1st New York Light Artillery are examples of this. Some Northern states raised "independent" batteries, which were not attached to an artillery regiment. New York supplied fifteen independent batteries including Captain Andrew Cowan's 1st New York Battery and Captain Patrick Hart's 15th New York Battery, both of which fought at Gettysburg. Confederate batteries were, for the most part, labeled by the nicknames of where they were raised or by the name of the battery commander. The "King William Artillery", commanded by Captain W.P. Carter, was typical of a Virginia organization. In the same battalion were the "Jeff Davis Artillery" from Alabama, and the "Morris Artillery" and "Orange Artillery" from Virginia.

There were several different types of field cannon developed prior to and during the war with many different nomenclatures. Four distinctive models were used in the field:

12-pounder bronze gun, Model of 1857. Commonly referred to as the "Napoleon", this bronze smoothbore cannon fired a twelve-pound ball and was considered a light gun though each weighed an average of 1,200 pounds. This powerful cannon could fire explosive shell and solid shot up to a mile and charges of canister up to 300 yards with accuracy. The Napoleon was a favorite amongst some Northern artillerists because of its firepower and reliability. Two Union batteries armed with Napoleons at Gettysburg were very effective in holding back Confederate infantry attacks and knocking down opposing Southern batteries. Battery G, 4th US repeatedly slowed Confederate infantry attacks against the Eleventh Corps line on July 1 while Captain Hubert Dilger's Battery G, 1st Ohio Light Artillery almost annihilated two Confederate batteries with accurate and punishing counter-battery fire at long distance. Most Union Napoleons were manufactured in Massachusetts by the Ames Company and the Revere Copper Company. Confederate industry replicated the Napoleon design at several foundries in Tennessee, Louisiana, Mississippi, Virginia, Georgia and South Carolina. The Confederate design differed slightly from Union-made guns but fired the same twelve pound shot, shell and canister rounds used in Union manufactured guns.

2.9-inch (10-pounder) Parrott Rifle. This iron cannon was rifled and fired an elongated shell made specifically for the gun. Designed before the war by Captain Robert Parker Parrott, this gun was longer than a Napoleon, sleeker in design, and distinguishable by a thick band of iron wrapped around the breech. The Parrott design went through several improvements during the war and was changed in 1863 to a larger 3-inch bore and matching Parrott shell. The 3-inch Parrott was standardized the following year and most 2.9-inch guns were withdrawn from service. Parrott Rifles were manufactured by the West Point Arsenal in Cold Spring, New York and also made in 20 and 32-pounder sizes. The 10-pounder Parrotts used during the Gettysburg Campaign had an effective range of over 2,000 yards. The 5th New York Battery was composed of six 20-pounder Parrotts. Confederate copies of the Parrott Rifle were produced by the Noble Brothers Foundry and the Macon Arsenal in Georgia. Parrott Rifles in 10 and 20-pounder sizes were sprinkled throughout some Southern batteries.

3-inch Wrought Iron Gun. This sleek weapon was also called the 3-inch Ordnance Rifle and was designed by John Griffen, superintendent of the Safe Harbor Iron Works in Pennsylvania. The initial design was built by the Phoenix Iron Company of Phoenixville, Pennsylvania which manufactured most of the 3-inch Rifles used in the Union Armies. This iron gun was similar in length to the Parrott Rifle, fired an elongated shell, and was deadly accurate up to a mile. Much lighter than the Napoleon, the gun weighed an average of 800 pounds and could be easily transported and manhandled by its crew. Only a limited number of copies of the Ordnance Rifle were produced at Confederate arsenals.

Model 1841 12-pounder Howitzers. A pre-war bronze gun dating back to the 1840's, a number of howitzers were still in use by the Army of Northern Virginia during the Gettysburg Campaign. The barrels of these guns are several inches shorter than other artillery pieces giving them a stubby appearance. These powerful guns packed a whallop at close range but were not desirable for long range work. Larger 24-pounder field howitzers were also produced and though some appeared at Gettysburg, their use was mostly limited to forts and stationary defenses by this time of the war.

There were a number of other unusual guns in use by both sides during the campaign. Two of these are:

3.8-inch James Rifle. The James Rifle was a bronze rifle similar in shape to the 3-inch Ordnance Rifle, and was produced by the Ames Manufacturing Company of Chicopee, Massachusetts. It was not a widely used cannon in either army, though the 2nd Connecticut Battery was armed them at Gettysburg. The James Rifle fired a 14-pound elongated shell and were accurate up to 1,700 yards.

An artillery shell was affixed to a wooden base and a cloth bag filled with one to two pounds of black powder. The shell was placed into the muzzle of the cannon and rammed into the breech. The bag was pierced with a sharp wire through the vent at the breech and ignited by a friction primer- a copper tube filled with ignition powder & fulminate of mercury. The primer was attached to a lanyard that when pulled, drew a serrated wire through the primer igniting the charge. An efficient gun crew could load and fire up to three rounds per minute. This deadly efficiency was never more evident than on July 3rd during Pickett's Charge. A variety of ammunition was used against the Confederate infantry formations. One solid shot plowed into Company I, 53rd Virginia Infantry knocking out 12 men. As the Confederates swarmed up to the Union positions, Union gunners desperately loaded and fired double charges of canister into the gray ranks with devastating results. It is no wonder that infantrymen had such high respect, and loathing, for the big guns.

A battery was an intricate organization of men, horses, and ordnance. There were multiple duties for each man to perform when not in battle including care of the horses, gun and carriage maintenance, and routine stock duties. In battle, each man had a specific assignment to serve the gun, though many were cross-trained and could perform other duties when required. One battery in the Union army consisted of six cannon, all of similar type and caliber and each with its own limber and caisson. Teams of six horses were used to pull the limbers and caissons that held ammunition chests containing the different types of shells used in each gun. The gunners walked during the march or trotted alongside the limbers when moving into a position. Only when the situation called for fast movement did they ride on the limbers and caissons when going into battle. Once in position, the gunners would unlimber the cannon and the limber would move to a position directly behind the gun. The caisson team would move to a location behind the limber to await further orders.

Confederate batteries were smaller, composed of only four guns and often of different types and calibers. For example, Captain Charles Fry's Virginia Battery, the "Orange Artillery", had two 3-inch Ordnance Rifles and two 10-pounder Parrott Rifles. Captain Hugh Ross' Georgia Battery had one Napoleon, three Parrott Rifles, and one Naval Parrott Rifle. Due to a scarcity of horse reserves in the South, Confederate batteries were forced to limit their horse teams to only four animals. Mules were used when horses were unavailable, but they were not considered a satisfactory substitute as they were more difficult to control.

In the Army of the Potomac, the artillery was organized by brigades. One brigade was commanded by a major, lt. colonel or colonel though several were commanded by captains, and was composed of four to five batteries. Every corps had one artillery brigade assigned to it for the use of the corps commander. The artillery brigade commander was responsible for posting his batteries and making certain that each was properly serviced and supplied. Two brigades of horse artillery were assigned to the Army of the Potomac's Cavalry Corps. The army also had a well organized Artillery Reserve composed of five brigades. These reserve brigades supplied extra batteries to support the batteries assigned to the infantry corps, and added an extra amount of firepower when and where it was needed.

The Army of Northern Virginia organized its artillery into battalions, each commanded by a major or colonel. One battalion was composed of four batteries and one battalion was assigned to an infantry division. For example, Major William T. Poague's Battalion, assigned to Pender's Division of Hills Corps, was composed of the Albemarle (Virginia) Battery, the Charlotte (North Carolina) Artillery, the Madison (Mississippi) Light Artillery, and Brooke's Virginia Battery. In addition, each of the three army corps had an artillery reserve of two battalions. Despite the larger number of artillery organizations in Army of Northern Virginia, the Union held the advantage in the actual number of guns present during the battle. Many of the Confederate batteries were understrength and missing their total compliment of cannon.

Civil War Siege and Garrison, and Seacoast Artillery

Heavy artillery was divided into two classes -- siege and garrison, and seacoast. The siege and garrison pieces could be moved on carriages by road, while the seacoast artillery was much heavier and had to be moved on special carriages. There were times where siege guns were brought into action and used on the battlefield, such as Shiloh and Malvern Hill.

As a siege gun, the smoothbores were eventually replaced or rifled, due to the greater accuracy of the rifled gun. Their destructive firepower also made the old brick and stone forts of a thing of the past. Although attempts were made to convert some of these smoothbores to rifled guns by reinforcing them with wrought-iron rings, the cast iron of the gun was not strong enough to stand the increased pressures. (Many of these converted guns burst and proved to be deadly to the crews.)

As in heavy artillery, mortars were classed as "siege" or "seacoast" guns. The 8-inch and light model 10-inch mortar siege guns, while cumbersome, could be transported on mortar wagons. The longer and heavier models of the 10-inch and the giant 13-inch mortars were classified as "seacoast," as they could only be moved with great difficulty by rail or ship. Mortars typically used spherical shells, and both timed and percussion fuses. Although experiments were made using canister shot as shells, the gun crews were unable to remain at their guns under the shower of metal. See also Civil War Artillery and Cannon: Field, Garrison and Siege, and Seacoast.

Although there was great technological advances made during the Civil War, such as the improved casting method by Major Rodman, real progress would be witnessed later with the introduction of nitroglycerin-based propellants. Still, the artillery proved pivotal and deadly in almost every major engagement during the war. From the massed Union batteries at Stones River and Malvern Hill, to the work of a few guns during Hood's 1864 Campaign, the cannoneers bravely and laboriously performed their duty.