In the early days of naval warfare most shipboard guns were small man-killers for use at close quarters. As the size of guns increased and their numbers decreased, small guns were retained for use in the fighting tops of larger vessels to fire down on the exposed crews working the top deck of an enemy ship. Such weapons were a variety of types: those in the U.S. Navy were called howitzers or coehorns. Smaller guns, known as swivels, were mounted on the rail of small warships and boats.
Boat guns, usually small Army pieces, swivels, or coehorns, were used to arm small craft for operations against an enemy with little naval force. For such operations, boats of light draft were required, and for them, guns that combined the greatest power with the least weight.
Boat guns in the early U.S. Navy were carronades. A six-pounder carronade on board the sloop Yorktown was used for her launch, while a 12-pounder carronade of English manufacture served the same purpose for a launch of the ship-of-the-line Columbus. Carronades ere made of iron, however, and consequently were really too heavy for boat use.1
The British embarked field artillery pieces on ships of the line for amphibious operations along the American coastline during the War of 1812. These included light six-pounders weighing approximately 616 pounds, and 5.5-inch howitzers. They were manned by crews of 15 men and were landed in a launch and pinnace for each gun and its limber.
The need for a boat gun designed specifically for the U.S. Navy was demonstrated conclusively during the Mexican War (1846-1848), in which the U.S. Navy blockade required operations in waters too shallow for even the smallest sloops; coastal craft were pressed into service but there was no suitable armament available. The U.S. Navy met the shortage during the war by using Army 6- and 12-pounder field pieces and mountain howitzers, small carronades, and some old, light 4.4-inch howitzers from storehouses in the yards.2
After the war, Lieutenant John A. Dahlgren, then at the Washington Navy Yard, was directed to evaluate the Army’s mountain howitzer for use in the fighting tops of ships and as a boat gun, but the results were unsatisfactory. Two such mountain howitzers with Navy stampings survive at the Washington Navy Yard and may have been the ones used in the tests.3 With the support of Commodore Lewis Warrington, Chief of the Bureau of Ordnance and Hydrography, and despite what Dahlgren described as “great objections” from other quarters, in 1848 he began work on a new naval howitzer.'1
He decided to replace the carronade with a smaller, lighter piece, without increasing the recoil. He was willing to sacrifice long-range fire and the ability to penetrate heavy planking on warships, because the new weapons had other missions: to attack small lightly armed vessels, engage other armed boats, cover the landing of regular troops, and accompany ships’ landing parties.5
On 21 February 1848, Dahlgren submitted a draft design of a small bronze 12-pounder weighing 276.5 pounds, somewhat larger than the Army’s mountain howitzer. (See Figure 1.)
The first service Dahlgren boat howitzer, complete with lock, sight, carriage, ammunition, and equipment, was sent to Boston on 6 June 1849 for the sloop John Adams, then fitting out for service off Africa.6 The bronze-founder for the howitzers, at least in the early stage of production, was A. Davis.
Critics believed that the new howitzers—particularly the lightest one— were too light to be effective. Dahlgren answered by pointing out that the “purpose of boat guns is to operate against personnel merely . . . assuming musket range to extend to four hundred yards, the light twelve is effective considerably beyond this distance.. . . The object in view is to ascertain the minimum weight that can be used. . ..” in order to have a gun that could be landed quickly and yet out-range musket fire.7
Objections to the Dahlgren-designed boat howitzers subsided after a year of trials on board Navy vessels, and in December 1850, Secretary of the Navy William Graham authorized their formal adoption.
In his 1852 published report, Dahlgren said that insufficient time had been allowed for testing, but noted with satisfaction that the demand was far greater than the supply, the result being that there were seldom more than one per ship. Despite poor facilities and few workers, 40 howitzers had been produced, of which 30 were then in service. A new building was completed and occupied in May 1854. Still standing at the Washington Navy Yard, it provided space for additional steam-driven machinery and separate rooms for the fitting of ammunition.
Three different versions of Dahlgren’s howitzer were produced:
►A 12-pounder (4.62-inch bore) light howitzer of 430 pounds (with boat carriage, 660 pounds)
►A heavy (as Dahlgren called it) 12- pounder, also with a 4.62-inch bore, that was confusingly sometimes referred to as the “medium” 12-pounder, that weighed 760 pounds—1,200 with its boat carriage
►A 24-pounder (5.82-inch bore) of 1,310 pounds—2,000 pounds with its boat carriage
Other types appeared later, including the “small” 12-pounder weighing approximately 300 pounds; and rifled guns—a 12-pounder (3.4-inch bore and 880 pounds) and a 20-pounder (4.0-inch bore and 1,340 pounds). The 12-pounder was ultimately given multigroove rifling; the 20-pounder had three wide grooves of rifling. At least seven steel 12-pounder rifled howitzers were also made.8
All Dahlgren boat howitzers were chambered (frustum of a cone) at the bottom of the bore. In external appearance they were smooth, with no reinforcing rings and no muzzle swell. The breech plate was in the form of a portion of a sphere. Around the charge, the gun was a cylinder to a point in front of the seat of the projectile; from there forward to the muzzle, the gun was in the form of a truncated cone.
The first models of the boat howitzer had trunnions and a loop or “navel ring” underneath the gun. The trunnions were superior to the loop in containing recoil but required a large carriage, and the need to save space in the small boats won out; subsequent production models, with but one exception, were secured to their carriage by the loop underneath the gun.
Elevation was adjusted using a screw that passed through the cascabel knob. The front sight was located on the top of the muzzle, and the rear sight moved up and down in a hole drilled in a mass cast on the top of the breech.
As with other naval guns of the period, the Dahlgren boat howitzers were Fitted with a perforated percussion hammer or lock that Dahlgren invented while he was on coast survey duty in 1835; he tested it on the USS Cumberland between 1843 and 1846. The new lock had been officially submitted to the Bureau of Ordnance and Hydrography in 1847 and subsequently used on larger guns of the experimental battery at the Washington Navy Yard.9
The 24-pounder Dahlgren boat howitzer was intended for use in the launches carried by 74-gun ships and large frigates. While the launch of a 74 could easily support a 2,000-pound gun—which would mean a 32-pounder howitzer— such ships were rare in the U.S. Navy. The heavy 12-pounder was designed specifically for the launches of frigates— and could be used for cutters of 74s— and as a field piece. It was too heavy for sloop launches, however; and since there were then three classes of sloops in the U.S. Navy, the light 12-pounder was developed specifically for them. It could also be employed on cutters carried by frigates, and secondarily on cutters carried on board 74s. The small 12-pounder that weighed 300 pounds was developed for launches of brigs, cutters, and as a field piece.
The 12-pounder was mounted on both boat and field carriages. According to a directive of Secretary of the Navy Graham of 17 December 1850, each ship of the line and frigate was to have one 24- pounder boat gun and one 12-pounder mounted as a field piece, but with a boat carriage available so that it could be used in that configuration if necessary. Each vessel below frigate and of rate not less than second-class sloop-of-war was to have one 12-pounder boat gun mounted for boat service. Depending on their availability and the service in which the vessels might be employed, it might in the future “be deemed proper to extend the allowance of boat guns to the smallest class of sloops-of-war, and field pieces to first-class sloops. . . .”10
On 24 March 1851, the first 24- pounder howitzer was sent to the steam frigate Susquehanna. On 18 April, a 12- pounder howitzer on field carriage was sent to Annapolis, probably for drill, as by that time Dahlgren was making regular trips to the Naval Academy as professor of gunnery.
Placed in the bow of a launch (see Figure 2), the Dahlgren boat howitzer could be pivoted 120° without altering the direction of the vessel. It could also provide rapid fire against small boats or light vessels, and covering fire in an amphibious assault.
The 12-pounder was also designed to provide ground fire support to accompanying parties of disembarked seamen, since it could be rapidly mounted on the field carriage, and later returned to onboard use. Eight to ten men could accomplish these changes in two to three minutes.11 The field carriage weighed less than 500 pounds, only about half that for Army pieces of comparable caliber. Since in naval practice the guns were hauled by sailors rather than horses, a small wheel was added at the end of the trail for ease of movement, and the howitzer was pulled by a drag rope attached to the trail. The field carriage was assembled using screw nuts to allow it to be taken apart and put together rapidly.
The howitzer was essentially an antipersonnel weapon; no solid shot was included in its ammunition, which consisted of shell, cannister, and Shrapnel or spherical case. (Cannister was made up of iron shot 1.07 inches in diameter packed in a tin case; Shrapnel contained 80 lead musket balls in the 12-pounder and 175 balls in the 24-pounder.)
As early as 1849, Dahlgren was advocating the use of spherical case ammunition in the boat howitzers, noting that “Where a solid shot would knock over a few men at most, the explosion of the case spreads 30 to 40 balls capable of doing ten times as much execution.” The effectiveness of case ammunition had been conclusively demonstrated in the Battle of Buena Vista during the Mexican War. The fixed ammunition was carried in boxes lashed to the carriage—as many as 72 rounds could be available.
The Dahlgren howitzers could be fired rapidly. Dahlgren stated that during testing and in drills the 12-pounders were fired at rates of seven and eight times a minute and that there were instances of rates of ten times a minute or better. The maximum firing rate for cannister from a field carriage was eight times a minute, but the usual rate was three to four times a minute. In the limited confines of a launch, where the howitzer was more difficult to service, the maximum sustained rate was five times a minute.
Ranges for the 12-pounder heavy (at 5° elevation) were 1,150 yards with Shrapnel and 1,085 yards with shell. The 24-pounder ranged (same elevation) to 1,308 and 1,270 yards, respectively. No range figures are available for the light or small 12-pounders. The 3.4-inch rifled 12-pounder charged with one pound of powder, at 5° elevation threw its 12- pound shell a distance of 1,770 yards.12 By 1856 the new Bormann fuses (designed by a Belgian artillery officer) were being used for Dahlgren howitzer shells.
Dahlgren summed up the advantages of his howitzers in 1859 when he wrote to a Virginian who had inquired (in the aftermath of John Brown’s raid on Harper’s Ferry) about using them for riot control Dahlgren stated that the howitzers could be worked as rapidly as field artillery, “maintaining the most rapid rate of firing known to any system of artillery, whether foot or horse. . . .” Their metal was superior; their carriages only one-half the weight of those used by the Army; and they could be handled by a few men, rather than a team of horses. Finally, they were “powerful and not costly.”
The 12-pounder Dahlgren boat howitzers saw their first service use on board the USS Constitution off the west coast of Africa in September 1853, and the USS Plymouth used them at Shanghai in April 1854. Twelve Dahlgren boat howitzers (eleven 12-pounders and one 24) were included in the armament of the ships in Commodore Matthew Calbraith Perry’s expedition to Japan in 1853-1854. Landing parties took them ashore where they impressed the Japanese with Western technological superiority.
The advantage of the howitzers in combat was demonstrated at the end of November 1856 in the attack against the Barrier Forts near Canton, China, by the U.S. Navy warships Portsmouth and Levant. Subsequent boat attacks and landing parties of several hundred men succeeded in neutralizing and then capturing the four Chinese forts, taking and spiking 176 shore cannon in the process.13 Commander A. H. Foote, captain of the Portsmouth, who led the assault, made special mention of the howitzers: “Those pieces of our squadron have gained everlasting fame. The English and French say they are the best pieces that they have ever seen. The howitzers of the Portsmouth made about 2,000 Chinese take a right-about-face and run.”
By 1860, U.S. Navy vessels were armed with Dahlgren boat howitzers as follows: ships of the line and first-class propeller frigates had two 24-pounders of 1,300 pounds with a boat carriage, one for each of their two launches. Both first- and second-class cutters had a 12-pounder of 750 pounds with both boat and field carriages. In all other frigates, each of the two launches had a 12-pounder of 750 pounds with boat and field carriage for their launches. The first-class cutter had a 12-pounder of 430 pounds with a boat carriage. In first- and second-class sailing sloops, the launch had a 12-pounder of 750 pounds with boat and field carriages. In all other sloops and brigs, the launch had a 12-pounder of 430 pounds with boat and field carriages.
Large numbers of the Dahlgren boat howitzers were cast during the Civil War. In 1878, Commodore William N. Jeffers, Chief of the Ordnance Bureau, gave the total number made for the Navy as 4,001; of this number 3,339 were “on hand, serviceable and in use.”
The Washington Navy Yard could not keep up with the wartime demand for the howitzers. As a result, both Charles T. Ames of Chicopee, Massachusetts, and Cyrus Alger & Co. of Boston also produced them under private contract for the Navy. There is no evidence of manufacture of Dahlgren boat howitzers in the Confederacy during the Civil War.
The small and light 12-pounders were not favored during the war (the manufacture of the lights was for the most part discontinued), and the 24-pounders, although officially boat armament, usually remained on board ship. But the extremely effective heavy 12-pounder was considered the best boat gun in the world.14
Their rapid rate of fire and the close quarters of river warfare made the boat howitzers a natural choice for such service during the Civil War. For example, the Wissahickon, one of the Unadilla class (the “90-Day Gunboats” hurriedly constructed after the outbreak of the Civil War), was armed with a 20-pounder Parrott rifle on the top-gallant forecastle, an Xl-inch Dahlgren in pivot abaft the fore mast, and two Dahlgren 24-pounder howitzers on the quarterdeck.15 Some of the 24-pounders used on smaller Union vessels in river work appear to have been mounted on broadside carriages.
Dahlgren boat howitzers were also used ashore in the South during the winter of 1864-1865 by the Naval Brigade of Admiral Dahlgren’s South Atlantic Blockading Squadron. The 500-man brigade, commanded by Commander George H. Preble, had two naval field batteries, each with four howitzers drawn from the naval battery on Morris Island and from ships of the South Atlantic Blockading Squadron.
The brigade was embarked on three steamers that proceeded up the Broad River; the brigade and its howitzers were landed within less than 30 minutes at Boyd’s Neck, South Carolina, on 29 November. The brigade fought in a heavy action alongside Union Army forces under Brigadier Generals E. E. Potter and John P. Hatch at Honey Hill, near Grahamville, on 30 November. It then accompanied the land force to Tulifinny Cross Roads where it took part in other actions on 6 and 9 December that helped divert Confederate forces opposing Sherman’s march to the sea.16
Commodore H. A. Wise, Chief of the Bureau of Ordnance, best summed up the effectiveness of the boat howitzers during the Civil War. He noted that no changes had been deemed necessary in them and that whenever called into use, “either in detached boat expeditions on our sea-coast, or on board the light- draught cruisers of our inland rivers, they have done excellent service.”
There were instances of the use of the boat howitzer by regular land forces as early as 1861. On 15 May, the 71st Regiment of the New York Militia was assigned to duty at the Washington Navy Yard. While there, the men learned to work the boat howitzers. When called to Manassas for what became the First Battle of Bull Run, the unit borrowed two 12-pounders, dragging them manually as would a naval landing party. During the battle, the Dahlgrens were served by Company I of the 71st as part of General Ambrose Burnside’s brigade. During the retreat after the Union defeat, the 71st formed a hollow square around the howitzers and was bringing them away in orderly fashion. It proved impossible to drag the two Dahlgrens up the east bank of Cub Run, however, and they were abandoned. These were probably the captured Dahlgrens issued on 15 August 1861 to a newly formed Confederate battery from Salisbury, North Carolina.
Other navies had shown considerable interest in the Dahlgren boat howitzers before the Civil War, and some of them copied it. As early as 1850 the Bureau of Ordnance ordered Dahlgren to make a model of one of them with carriage for the French Minister of Marine. Perry’s 1854 expedition to Japan had left one of the Saratoga's 12- pounders behind at the request of the Japanese government.
In 1860, the Niagara delivered a battery of the howitzers to Japan as a gift from the United States. Commodore Wise, who was on the 1860 voyage to Japan, related to Dahlgren that the Japanese had already copied his design. He reported that he had seen seventeen 12- pounders, complete with field carriages, and was told that the Japanese had a thousand more of the same sort. Wise later counted 46 in one fort near Tokyo.
The Dahlgren boat howitzers continued in U.S. Navy service well past the Civil War. In his annual report of 1869, the Chief of the Bureau of Ordnance noted the need to manufacture additional 12-pounder howitzers of 430 pounds to replace 24-pounders that weighed 750 pounds. This was because the boats being built for the Navy were too sharp to provide the buoyancy needed for the larger pieces.
It was not until the 1870s that the Navy began to change over to new breech-loading howitzers. In 1873 the Bureau of Ordnance prepared models of two new classes of breech-loading boat howitzers for trial, both of which used metallic cartridges. The lighter version, which weighed 350 pounds, was ultimately adopted. The 1880 Ordnance Instructions describe both it and the Dahlgren muzzle-loading, rifled 3.4-inch (12-pounder) and 4-inch (20-pounder). Evidently both were still in service as of that date.
Dependable and long in service, certainly the Dahlgren boat howitzers were the finest boat guns of their time in the world.
1. U.S. National Archives, Record Group 74, Entry 117.
2. John A. Dahlgren, System of Boat Armament in the United States Navy (Philadelphia: King & Baird, 1856), p. 10.
3. James C. Hazlett, Edwin Olmstead, and M. Hume Parks, Field Artillery Pieces of the Civil War (Newark. DE: University of Delaware Press, 1983), p. 141.
4. Madeleine V. Dahlgren, Memoir of John A. Dahlgren (New York: Charles L. Webster & Co., 1891), pp. 133 and 143.
5. John A. Dahlgren, op. cit., p. 51; and Report of Lieutenant John Dahlgren to Commodore Warrington, 9 April 1849, in bindings, U.S. National Archives, Record Group 74, Entry 201, No. 1, p. 19. (Hereinafter cited by cover title, “Bronze Boat Howitzers.”)
6. Madeleine V. Dahlgren, op. cit., p. 133.; Emmons, The Navy of the United States (Washington, D.C.: Gideon and Co., 1853), p. 26; and John A. Dahlgren, op. cit., p. 13. The John Adams, a second-class sloop built in 1830, was armed with four 8-inch and fourteen 32-pounder guns.
7. Madeline V. Dahlgren, op. cit., p. 143. Italics in original.
8. U. S., National Archives, Record Group 74, Entry 201, Box 5, Item 5: Letters and Reports on Ordnance Subjects by John A. Dahlgren (Letter of 2 April 1861 from Dahlgren to Chief of the Bureau of Ordnance and Hydrography, Captain George A. Magruder.
9. John A. Dahlgren, Ordnance Memoranda. Naval percussion locks and primers, particularly those of the United States. (Philadelphia: A. Hart, 1853), pp. 32-34.
10. John A. Dahlgren, System of Boat Armament in the United States Navy, p. 21.
11. Letters from Dahlgren to Chief of the Bureau of Ordnance and Hydrography, Captain Andrew Harwood, on 14 October 1861 and 11 January 1862. U.S., National Archives, Record Group 74, Entry 201, Box 2, Item 5: “Reports and Letters on Ordnance Subjects by John A. Dahlgren.”
12. Ordnance Instructions for the U.S. Navy (1866), Appendix, pp. xvi and xvii. The 20-pounder threw its shell 1,960 yards at 5° elevation using a two-pound powder charge.
13. Dudley W. Knox, A History of the United States Navy (New York: G. P. Putnam’s Sons, 1936), pp. 186-187.
14. Warren Ripley, Artillery and Ammunition of the Civil War (New York: Van Nostrand Reinhold, 1970), pp. 88-89.
15. Letter from Captain John de Camp to Dahlgren, 18 August 1862. Library of Congress, Dahlgren Papers, Box 5.
16. Letter from John P. Hatch to Commander George H. Preble, 4 October 1866, in Library of Congress, Dahlgren Papers, Box 6. Also Patricia L. Faust, ed.. Historical Times Illustrated Encyclopedia of the Civil War (New York: Harper and Row, 1986), pp. 349- 350, 600, For details see Official Records of the Union and Confederate Navies in the War of the Rebellion (Washington, D.C.: U.S. Government Printing Office, 1903), Series I, Vol. 16, pp. 61-111. There is a map of the engagement on page 67.