Although small in comparison to other artillery pieces, the 1861 Mountain Howitzer (photo at right) used by the North and the South, was one of the most important fieldpieces to see action in the Civil War.  It was a small versatile gun yet still packed quite a punch.  The design for the mountain howitzer was based on French models.  First introduced in 1835 by President Andrew Jackson's secretary of war, Lewis Cass, it was originally intended for use in the Seminole Wars.  Cyrus Alger & Co. produced the first 12 model 1835 guns, with the model 1841 coming out later.  After 1863, the Ames Manufacturing Company also produced the howitzer for the Union.

The howitzer's barrel and carriage together weighed only 507 pounds.  A standard cannon had a 4.62-inch bore (12 pounder).  The Mountain Howitzer's also had a 4.62 and fired the same ammunition as the Napoleons but weighed 1000 pounds less.  The mountain howitzer is a smooth bore gun with a turned metal 32.9 inch long barrel that was 1.5 inches thick and weighed only 220 pounds.  The barrel went through 10 different design versions during its use.  At the start of the Civil War, a Mountain Howitzer's brass barrel cost the U.S. Army only $165 each.  The Tredegar Iron Works in Richmond had to teach itself how to make the versatile weapon.  Cast iron had to be substituted for scarce bronze, but the iron available was not always of the best quality and was apt to crack under pressure.  Tredegar produced as many as 21 pieces in 1862 to 1863.

When Maj. John S. Mosby's (CSA) rangers first saw the little brass mountain howitzer that Gen. Stuart had presented them, they laughed and joked that it was too small to be a cannon but too large to fit in their holsters.  They soon learned that the short-barreled, large-caliber weapon was ideal for their warfare.  With a crew of six to eight artillery men, rounds can be fired safely at a rate of one per minute.  This rate of fire can be and probably was increased during battle.  At a five degree elevation and with a half-pound charge, it could throw a shell 900 yards.  Although a smooth bore is not accurate and needs to be resighted after each firing, its three inch ball, canister or shell can still do its job when it hits a target.  Although not fully documented, the life of the barrel was estimated at around 1000 rounds fired.

The little cannons were light enough to be pulled rapidly on raids with just one horse.  It was usually mounted on a prairie carriage, also known as type 3 carriage that was 61 inches long and weighed 157 pounds.  The wheels were 42 inches in diameter and weighed 65 pounds apiece.  During a battle, it can be easily moved by the artillery crew; but additionally, the cannon can be disassembled and mobilized by three pack animals when long hauls are called for.  The entire cannon can be assembled and disassembled in minutes by simply pulling pins without the need of tools. All artillery supplies are kept in a limber box and carried by a pack animal or by the artillery crew on the battle field.  The size of the piece and its necessary accoutrements eliminates the need for a large limber drawn by horses.  The ammunition was carried in narrow boxes holding eight rounds each and weighing 112 pounds when fully packed.  One of these ammunition boxes was strapped to each side of a packsaddle.  When packed and on the move, one mule carried the tube and the shafts, and the other the carriage, implements, and wheels then the last mule carried the ammunition.

References:
1860 U.S. Army Ordnance Manual
Arms And Equipment Of The Civil War
Lords Civil War Collectors Encyclopedia