The War of 1812 once-again pitted the British Empire against its former colonies making up the United States. This led to a ramping up of war-making products and, in 1811, the "Columbiad" gun was introduced by the United States. These heavy weapons were affixed to fortifications in defense of British forces, particularly approaching naval elements, and featured within the confines of forts along the American East and Southern coasts. The guns were powerful systems capable of reaching out to the enemy at range and firing both shell or shot. Mainly used for defensive purposes, there was little stopping a crew from utilizing the gun as an offensive-minded implement. The type was in circulation by the time of the American Civil War (1861-1865) and used by both sides of the conflict in one way or another.
At their core, the guns were line-of-sight weapons with smoothbore barrels and loaded from the muzzle (i.e. muzzle-loading). Multiple personnel were required to provide the various functions in keeping the gun a viable battlefield system. The initial guns were adopted in 1811 (hence their model designation) and were offered in a modest 7.25" caliber. The weapons were capable of lobbing projectiles weighing as much as 50lbs some distance away and only their high procurement cost limited the reach of these early forms. Their importance in numbers was not truly realized until the build-up of war between the States after which an 8", 10", 15" and 20" models were manufactured beginning in 1958 and rifling (beneficial for ranged accuracy) was becoming commonplace for field guns of many types. With the increase in caliber came an increase in barrel thickness as well as powder charge used and, therefore, an increase in projectile weight (the 15" units fire a 400lb projectile and itself weight some 25 tons).
The weapons were typically set atop heavy-duty mountings that allowed for some wheeled traversal as well as elevation. This provided for some tactical flexibility but the guns were heavy and, nonetheless, cumbersome to wield in short order. In what became known as the "Rodman Process" after its developer, U.S. Army officer Thomas Rodman, the guns had a "band" wrapped around their existing barrel rear sections for added strength and this allowed evermore powerful charges to be used thus increasing a given projectiles range and destructive power. This also increased the resiliency of the iron guns that were prone to fracturing after sustained use. Of course the process served in allowing engineers to produce evermore powerful, and larger caliber, guns in time.
Beyond their used by Federal (Northern) forces of the Civil War, the Confederates managed to capture existing stocks of Columbiads from Federal arsenals when the secession of states began in early-1861 (South Carolina became the first in late-December 1860). Confederate foundries also took up local production of the gun in various calibers though quality was sometimes wanting and these weapons also lacked the reinforcement qualities of their Rodman-modified Union brethren for the most part. The Confederate inventory yielded both 8" and 10" type guns but only a small percentage of these were known to be rifled. Columbiads were present during the defense / occupation of Fort Sumter in Charleston Harbor, South Carolina - site where the first shots of the war were fired. Even though designed as line-of-sight field guns, the elevation reach and power of Columbiads saw some of the type used as mortar weapons, in this case the projectiles being lobbed along a higher trajectory than normal for an artillery gun.
Columbiads were in operational service up until the end of the Spanish-American War (1898) - by which point they fared poorly on the modern battlefield and given up in favor of rifled, breech-loaded types as quickly as they could be had.