In 1844 the US Navy decided to show off their newest acquisition, a steam-powered, propeller-driven war ship with a 12-inch experimental gun. On February 28, President John Tyler, members of Congress, newspaper reporters and other guest boarded the USS Princeton at the Washington Navy Yard. The group enjoyed a leisure cruise down the Potomac while the Princeton demonstrated her maneuvering ability and armament. On the return trip the ship passed Fort Washington as Captain Robert F. Stockton prepared to fire one last round from the 12-inch, 225-pounder gun called "Peacemaker." When fired, the gun burst wounding many guests and killing five observers including Navy Secretary Gilmer, Secretary of State Upshur and a Congressman.

A Board of Inquiry found that no person could be held responsible for the mishap but they did find fault with the gun. They also concluded that the present technology could not produce a safe large gun. Large gun manufacturing ceased and for a while it seemed that ship builders had won the war against the gun. Admiral John A. Dahlgren, of the U.S. Navy, believed that the manufacturing process had no effect on the strength of a gun and blamed gun failures on thin barrel design. He developed a bottle-shaped cannon with a thick breech to absorb the extreme pressure created by large powder charges.

Thomas Jackson Rodman graduated from the military academy in 1841 and was assigned to the Ordnance Department at Allegheny Arsenal in Pittsburgh. Shortly after the Princeton incident he began studying the properties of gunmetal and theorized that a cannon cooled from the inside would be stronger than those manufactured by the current method. Rodman devised a theory to account for both internal strains and imperfections, and for variations in the density, hardness, and tensile strength of the metal in cast iron cannon. His most outstanding contribution was the method he invented for cooling cannon castings.

It had been determined that in the casting of large iron cannon, the sequence of cooling and hardening, which began at the outer surface and progressed toward the interior, left the finished gun under a pattern of stress directed to the exterior. Since the pressures associated with firing were also directed radially outward from the bore, the total stress at the moment of firing sometimes exceeded the gun's limit of strain and caused the weapon to burst.

Basically, he brought back the hollow casting process but instead of a solid core he used a hollow tube. Water circulating through the tube cooled the bore while coals were piled against the mold to keep the outer surface hot. Rodman's manufacturing method, now known as the "wet chill process", forced the impurities outward while the outer metal shrank against the hardened interior. This method produced a gun wherein the inner layers were under considerable contraction, thus being very superior to the unchilled cast guns which so often burst during firing. The net effect was that the firing of guns cooled in this manner actually reduced rather than increased the total stress on their metal.

This method of casting iron had negligible effect with regard to smaller weapons, such as those used in field artillery, but its effectiveness increased in direct proportion with the mass of iron involved in the cannon. Under Rodman's system of casting it became possible to produce one-piece iron guns in calibers as large as 15 and 20 inches.

He offered his idea to the government but it was rejected. Rodman obtained permission from his superiors to apply for a patent for hollow casting guns and arranged for the Fort Pitt foundry to cast and test his cannons. In 1849, it was found that cannons produced by his method were superior to all other guns produced in this country.

A Board of Captains convened in 1845 determined that the ships of the US Navy would be armed with 32-pdrs. and 8-in. shell-guns of different classes. By this Regulation there were established six descriptions of 32-pdrs., classed according to their weight, viz.: of 57wt',(or long gun,) of 51 ct., 46 cwt. 42 cwt., 32 cwt. and 27 cwt.; and two classes of 8-in. shell-guns-63 cwt. and 55 cwt. The first-class frigates carried 32-pdrs. of 57 cwt., and four 8-in. of 63 cwt. on the gun-deck, with 32-pdrs. of 32 cwt., four 8-in. of 55 cwt, and two 32-pdrs. of 51 cwt. (for chase,) on the spardeck. One or two of the heaviest ships had 32-pdrs. of 42cwt' on the spar-deck. The 32-pdr. of 46c wt was only designed for a few frigates of inferior rate.

Sloops of war were armed according to their size: the largest with 32-pdrs. of 42 cwt. and S-in. of 63 cvt.; the next with 32-pdrs. of 32cwt', and 8-in. of 55 wt., and the smallest with 32-pdrs. of 27 cwt.

In 1853, a Bureau Regulation, approved by the Navy Department, excluded the 32 of 51 cwt., and 8-in. of 55 cwt from the Armaments of Frigates, and directed that ten 8-inch of 63 wt. should be carried and collected in one division on the gun-deck. Line-of-battle ships had their gun-decks, whether two or three, and their spar-decks, armed respectively like those of frigates.

Since January, 1856, some of the ships had been armed in another manner, and the batteries of the new screw frigates were composed of new ordnance, differing in calibre and construction from the guns previously used.

The pivot-guns of the US Navy were the 64-pdr. and the 10-in. shell-gun of 86 cvt.. The 64-pdr. differed in no material particular from the English 68-pdr., except that the US gun had a bore of eight inches, and the British gun has a ball very nearly of the same dimensions, the latter was, consequently, about one-tenth of an inch larger than the American and proportionately heavier.

The largest steamers carried the 64-pdr., and some of the inferior classes the 10-in. shell gnu. The new Razee Corvettes, Constellation and Macedonian, had one of the latter on the forecastle and stern. The largest steamers had the 8-in shell-gun of 63 cwt in broadside, and those of inferior class the 8-in. of 55 cwt.

The US Naval shell-guns were of two patterns. The 10-in. of 86 ct., and the 8-in. of 63 cwt cast previously to 1851, followed the form prescribed by Paixhans; they were easily recognised by the straight muzzle common to the French canon-obusier of 22 cnt, and had no sight masses; they were not turned on the exterior, consequently retained the outer crust, which gave them a rough appearance. In 1851, some new 8-in. shell-guns of 63cwt. were cast, of the same length of bore as the other patterns, but following the external form of other Navy cannon. They were turned, had sight masses, a bell muzzle, and a stouter knob. The 8-in. of 55 cwt. was not introduced until after 1845. It resembled the new 8-in. of 63 wt, in external shape.

The average weight of 8-inch shells chosen from several thousand cast for service was found to be 50.03 lbs; while the average weight of shells of the same description, for the general service, averaged 49.8 lbs. The content of powder was about 1.85 lb. The weight of 10-inch shells averaged 102 lbs., and the content of powder is about 4 lbs.

Ranges of United States naval smoothbores of 1866
Caliber Point
in yards
Elevation Range
in yards
32-pounder of 42 cwt 3131,756
8-inch of 63 cwt 3301,770
IX-inch shell gun 35015°3,450
X-inch shell gun 34011°3,000
XI-inch shell gun 29515°2,650
XV-inch shell gun 3002,100
Ranges of United States naval rifles in 1866
Caliber Elevation Range
in yards
20-pounder Parrott15°4,400
30-pounder Parrott25°6,700
100-pounder Parrott25°7,180
By the time of the Civil War field artillery was divided into two categories - smoothbores and rifles. The difference was found in the bore - the inner surface of the barrel. The inner surface of the smoothbore was like a pipe, while the rifle's bore had grooves that spiraled the length of the barrel. The grooves, or rifling, caused the projectile to twist as it moved down the barrel and gave the rifle greater range and accuracy. The rifle's projectile would spin like a football as it moved through the air.

Smoothbore artillery pieces were designated by the size of the projectile they fired. The projectile fired by the 6-pounder was slightly larger than a baseball (3.58" diameter). The 12-pounder's was about the size of a softball (4.52" diameter).

Rifled artillery was a fairly new innovation when the war broke out. They had spiral grooves (rifling) that ran the length of the bore. These grooves caused the projectile to spin as it let the barrel. This spin gave the rifle greater range and accuracy than smoothbore guns. In addition to the rifle's range and accuracy, it also had a much greater impact when its projectile hit the target.

In accuracy and range the rifle of the 1860's far surpassed the smoothbores, but such tremendous advances were made in the next few decades with the introduction of new propellants and steel guns that the performances of the old rifles no longer seem remarkable. In the eighteenth century, a 24-pounder smoothbore could develop a muzzle velocity of about 1,700 feet per second. The 12-inch rifled cannon of the late 1800's had a muzzle velocity of 2,300 foot-seconds. In 1900, the Secretary of the Navy proudly reported that the new 12-inch guns for Maine-class battleships produced a muzzle velocity of 2,854 foot-seconds, using an 850-pound projectile and a charge of 360 pounds of smokeless powder. Such statistics elicit a chuckle from today's artilleryman.

During the War of the Rebellion, the Americans singularly distanced the Europeans in the science of gunnery. Not, indeed, that their weapons retained a higher degree of perfection than theirs, but that they exhibited unheard-of dimensions, and consequently attained hitherto unheard-of ranges. In point of grazing, plunging, oblique, or enfilading, or point-blank firing, the English, French, and Prussians have nothing to learn; but their cannon, howitzers, and mortars were mere pocket-pistols compared with the formidable engines of the American artillery. Nothing was more natural than to perceive them applying their audacious ingenuity to the science of gunnery. Witness the marvels of Parrott, Dahlgren, and Rodman. The Armstrong, Palliser, and Beaulieu guns were compelled to bow before their transatlantic rivals.

Columbiad Smoothbore Muzzle Loading [SML]

A Columbiad is large diameter smoothbore cannon invented by Colonel Bomford and first used in the War of 1812. The Columbia Foundry in Washington, D.C., originally produced the piece, thus the name Columbiad. It is, in fact, the Paixhan gun invented by Colonel Bomford. The cannons invented by him were further developed by Dahlgren, but were superseded by the Rodman type about the beginning of the civil war.

George Bomford, born in New York in 1780 [died in Boston, Massachusetts, 25 March 1848] entered from New York, was graduated from West Point in 1805, and became lieutenant in the corps of engineers. He served as assistant engineer on the fortifications of New York harbor in 1805-'8, then on the defenses of Chesapeake bay from 1808 till 1810, and as superintending engineer of the works on Governor's island from 1810 till 1812. During the War of 1812 with Great Britain, he served in the ordnance department, with the rank of major on the staff, was appointed assistant commissary-general of ordnance, 18 June 1812, and attached to the corps of engineers, 6 July 1812. He introduced bomb cannons, made on a pattern of his own invention, which were called columbiads, a form of heavy gun combining the qualities of gun, howitzer, and mortar. He was promoted Lieutenant-Colonel, 9 February 1815, and was continued on ordnance duty.

Perhaps the gun most commonly named at the oputbreak of the Civil War was the Columbiad. The Columbiad was of the class called sea-coast Cannon, and combined in itself the qualities of the gun, howitzer, and mortar: in other words, it is a long-chambered piece of ordnance, having the capacity to project shot or shell, with heavy charges of powder, at high angles of elevation. The Columbiad was a long, chambered piece, capable of projecting solid shot and shells, with heavy charges of powder, at high angles or elevation. They were equally suited to the defense of naval batteries along the coastal waterways and navigable rivers. These pieces were also mounted on wooden ships, ironclads, and monitors.

In 1844 the model of the Columbiad was changed, by lengthening the bore and increasing the weight of metal, to enable it to endure an increased charge of powder, or one-sixth the weight of the solid shot. Thus altered, they were found defective in strength, and in 1858 were degraded to the rank of shell guns, with diminished charges of powder. By the 1860s their place had been supplied by a new model, having no base-ring nor swell of the muzzle. The 8-inch carried a 10-pound ball; the 10-inch carried a 16-pound ball.

Three calibers of Columbiads were used in battle; the 8-inch (weight 9,240 pounds and 124 inches long), the 10-inch (weight 15,400 pounds and 126 inches long), and Captain T.J. Rodman's massive 15-inch Columbiad (weight 49,100 pounds and 190 inches long). A 12-inch and 20-inch Columbiad was also developed, but never employed in battle.

In 1822, Lieut.-Col. Henri Joseph Paixhan, of the French artillery, submitted, for the first time, his plan for throwing large heavy shells from long chambered guns (canons-a-bombes), in the same way that solid shot is thrown. Up to that time, shells fired from long pieces had been limited to the smaller calibres; and it remained for Paixhan to prove, after the greatest opposition on the part of others, that it was as practicable and almost as easy to throw shells to a great distance with slight elevations, as to throw shot. His piece, which was provided with a chamber, seems to have been designed more especially for the navy, though its importance as a defense against shipping in sea-coast defense was early perceived and taken advantage of; and his pieces, under the name of Paixhan guns, have been adopted in almost every service.

Paixhans published a book in 1822 explaining how his shell guns could easily destroy any wooden warship. In a trial firing two years afterwards Paixhans' guns did indeed destroy an old hulk, just as he had predicted. Thereupon, after appropriate deliberation lasting some thirteen years, the French navy decided in 1837 (just before the humiliation of 1841) to install the new shell-firing guns on shipboard. The Royal Navy and other European navies, including the Russian, swiftly followed suit. In 1841 the guns of his design were known as 'canons-obusiers' in the French Navy and 'Columbiads' in America.

Paixhan guns were invented by Colonel Bomford, of the United States Army. Being introduced into the French service by General Paixhan, they received his name, although he had nothing to do with their invention; however, he afterward improved upon them. They were first used in the war of 1812, and attracted universal notice. These guns are of enormous size, having a calibre of 8, 10, and 12 inches. They are made with great thickness at the breech, to enable them to withstand a large charge of powder and heavy ball. The largest of these guns, the 12-inch, loads with twelve pounds of powder, and carries a hollow shot weighing 112 pounds; its extreme range is 1550 yards. The 8-inch gun carries a solid shot of 68 pounds, at an elevation of 15 degrees, 3250 yards. The Paixhan guns are used with traversing beds ; they are thus driven up an-inclined railway, with from 3 to 4 degrees elevation, after each discharge. The great use of these heavy guns is in fracturing and splintering, dismounting guns, etc.; their range is usually not great.

Dahlgren Smoothbore Muzzle Loading [SML]

Captain Dahlgren, in his improvements of heavy ordnance, carried still farther the principle involved in the Paixhan gun -- that of strengthening the breech. His guns were universally used on ships of war of the Federal Navy.

  • 12-pounder bronze Dahlgren boat howitzer were initially intended for launches of frigates and as fieldpieces in amphibious landings, but they saw general use on nearly all types of ships and boats during the Civil war. A total of 456 boat howitzers of this heavy model were produced by Cyrus Alger & Co. (57), Ames Manufacturing Co. (202), and Washington Navy Yard (197) from 1849 to 1865. They
  • The 12-pounder bronze Dahlgren boat howitzer was one of Dahlgren's early designs. The bronze light smoothbore boat howitzer intended for launches of sloops-of-war, cutters, and as fieldpieces to be used in amphibious operations. A total of 183 howitzers of this light model were produced at Washington Navy Yard from 1848 to 1870; two others were made by Cyrus Alger & Co. of Boston, Massachusetts.
  • The 3.4-inch (12-pdr) Dahlgren rifled steel boat howitzer weighs 791 pounds, and has 12-groove rifling. Only twelve rifles of this type were made of steel.
  • The 3.4-inch (12-pounder) Dahlgren rifled bronze boat howitzer was designed by, and named for, John A. Dahlgren. A total of 423 3.4-inch rifled boat howitzers were produced from 1861 to 1865 at Washington Navy Yard. In a single Registry Number series and using the same castings as for the smoothbore heavy 12-pdr boat howitzer, 411 were cast of bronze and 12 of steel. Served by a crew of five, including a powder boy, a 1-pound powder charge propelled a 12-pound shell an expected range of 1,770 yards with 5 degrees elevation and a flight time of approximately 6 seconds.
  • The IX-inch Dahlgren smoothbore shell guns were the most reliable Navy cannon prior to, and during, the Civil War; only one was reported to have burst. Designed by John A. Dahlgren, 1185 were made during the years 1855-64 by six foundries. A full crew of 17 served this type cannon when in pivot or used singly. The expected ranges for 72.5-pound shell were up to 3,357 yards with a 10-pound propellant charge, 15 degrees elevation, and a flight time of 14.7 seconds. Thirteen-pound charges would provide ranges up to 3,450 yards for the same projectile. A 10-pound powder charge was to give 75-pound shrapnel ranges up to 1,690 yards at 5 degrees elevation and 5.9-seconds time of flight.
  • The XI-inch Dahlgren shell gun is the largest of the five shell gun types faithful to Dahlgren's patented design. Like the IX-inch, these proved extremely durable, the only known failure being one that burst during extreme proof at the 1,125th round. Eight foundries made 465 of this size during the years 1856-1864. A 20-pound propellant charge would give 136-pound shell ranges up to 3,650 yards at 15 degrees elevation and 16.5-second time of flight. A 15-pound charge was used to fire 141-pound shrapnel up to 1,710 yards at 5 degrees elevation and 5.6-second time of flight.

Rodman Smoothbore Muzzle Loading [SML]

A prototype 15-inch Rodman cannon was cast on December 23, 1859. During the gun trials 509 proofing rounds were fired without mishap. The first government purchase order for these 50,000 pound, 190 inch long weapons was issued in November 1861. During the Civil War the Rodman guns were the largest in the U. S. arsenal. Two 20-inch guns were purchased but the 15-inch gun, along with the 200 pounder (12-inch) muzzle loading Parrott Rifle, became the main seacoast armament.

  • The Columbiad was the Army's first gun capable of firing a heavy projectile. With a deafening roar, the Rodman cannon could hurl 440-pound shells for three miles. these guns were extremely heavy averaging 50,000 pounds. Their primary targets were naval vessels and landing craft. The largest stationary cannon was a Rodman weighing 117,000 pounds that shot a 1,000 pound projectile 4 1/2 miles.

In those days all muzzle-loading cannons were cast with a rear projection known as the knob. Ropes were attached to the knob to lift ordnance during manufacturing and mounting operations. When Fort Pitt was experimenting with the 10-inch gun they broke a number of knobs making it difficult to move and mount the cannon. Rodman developed a knob that was almost as large as the base of the piece and had only a narrow grove to accommodate lifting tackle. The button-shaped knob, with its lifting notches, is a distinctive feature of the large Rodman cannons and makes them easy to recognize.

Parrott Rifled Muzzle Loading (RML)

Captain Robert K. Parrott was born on October 5, 1804 and graduated from the United States Military Academy in 1824. After his graduation and until 1829, he was science instructor at the Military Academy. He was promoted to captain, Ordnance Department, in January of 1836, but resigned in October of that year to become Superintendent of the West Point Foundry at Cold Spring, New York. During the period 1836 to 1867, he invented and manufactured the Parrott guns and projectiles. By utilizing the process of hollow casting and cooling patented by General Rodman, he devised a method of employing shrunken hoops of wrought iron to strengthen the breech of big guns at the peak pressure area. It is easy to tell them apart for the Parrott has a reinforcing jacket around its breech. He was able to perfect the first United States rifled cannon in 1861.

His guns showed exceptional durability in the Civil War and were extensively used in several calibers. He also developed an expanding projectile for use with the guns. The 8-inch Parrott gun was termed "the most formidable service gun extant" by some ordnance experts. There were 10-, 20-, and 30-pounders and a 15-inch (400 pounder) with a range of 5,700 yards. For the 10, 20, and 30 pounder Parrott guns powder of too large a grain should not be used. The best powder for the projecting charge of these guns is what is called "mortar powder." Captain Parrott retired to private life in 1867 and died on December 24, 1877.

  • Parrotts used by Army field artillery were typically 10-pounders. Parrott rifles represented state-of-the-art, cutting-edge technology in 1862. They were first introduced in 1861 and were the first American rifled cannon. They were also the first truly successful rifled cannon because of the method used for reinforcement. It fired 10 lb. projectiles to a range of up to 1,900 yards. The Field Artillery version weighed 1,799 pounds.
  • The 3.67-inch (20-pdr) Navy Parrott rifle Model of 1861 was designed by, and named for, Robert Parker Parrott, owner of West Point Foundry at Cold Spring, New York, the 3.67-inch Parrott rifle has five-groove rifling with right hand twist. A total of 336 were manufactured for the U.S. Navy from 1861-65. It weighs 1,795 pounds. Served by a crew of seven, including a powder boy, a 19-pound shell propelled by a 2-pound charge of powder reached ranges of 4,400 yards with 15 degrees elevation and a flight time of approximately 17 seconds.
  • The 4.2-inch (30-pdr) Navy Parrott rifle has five groove rifling with right hand twist. It was made for the U.S. Navy during 1861-65 and weighs 3,500 pounds. Served by a crew of nine, including a powder boy, a charge of 3.25 pounds of black powder propelled a 29-pound shell up to 6,700 yards at 25 degrees elevation and 27 seconds of flight time.
  • The 5.3-inch (60-pdr) Navy Parrott rifle was used only by the Navy, with 110 of this size Parrott rifle were made in 1864 and 1865. Rifling is seven grooves of right hand twist. A 6-pound powder charge was used to propel 60-pound shell and 50-pound shell.
  • The 6.4-inch (100-pdr) Navy Parrott rifle were served at sea by a full crew of 17, including a powder man. Ten-pound powder charges provided expected ranges for 100-pound solid shot or long-range shells of about 6,900 yards at 25 degrees elevation and about 28 seconds time of flight. An 80-pound short shell had a range of 7,810 yards at 30 degrees elevation and 32.4-seconds time of flight. The Navy purchased 352 of these rifles from West Point Foundry during the years 1861-65. Rifling is nine grooves of right hand twist.
  • The 8-inch (100-pdr) Parrott Rifles weighed over 8 tons and used 16 pounds of powder to fire its 200-pound projectile 2,000 yards


The ammunition consisted of two parts - the projectile and the powder. The powder was pre-measured and was placed in flannel bags. For smoothbore guns, the projectile was strapped to a wooden plate (sabot), which stabilized it as it moved down the barrel and prevented it from tumbling through the air. The powder bag was tied to the sabot. For rifled artillery, the powder bag and projectile were separate.

Rifled weapons fired an elongated projectile called a bolt. These were particularly effective against material targets but were not as effective against men and animals. They tended to bury themselves as soon as they hit the ground.

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