Siege artillery is heavy artillery primarily used in military attacks on fortified positions. At the time of the American Civil War, the U.S. Army classified its artillery into three types, depending on the gun's weight and intended use. Field artillery were light pieces that often traveled with the armies. Siege and garrison artillery were heavy pieces that could be used either in attacking or defending fortified places. Seacoast artillery were the heaviest pieces and were intended to be used in permanent fortifications along the seaboard. They were primarily designed to fire on attacking warships. The distinctions are somewhat arbitrary, as field, siege and garrison, and seacoast artillery were all used in various attacks and defenses of fortifications. This article will focus on the use of heavy artillery in the attack of fortified places during the American Civil War.

Field artillery in the American Civil War refers to the artillery weapons, equipment, and practices used by the Artillery branch to support the infantry and cavalry forces in the field. It does not include siege artillery, use of artillery in fixed fortifications, or coastal or naval artillery. Nor does it include smaller, specialized artillery classified as small arms.