Dahlgren gun Dahlgren guns were muzzle loading naval artillery designed by Rear Admiral John A . Dahlgren USN ( November 13 , 1809 – July 12 , 1870 ) , mostly used in the period of the American Civil War . Dahlgren ' s design philosophy evolved from an accidental explosion in 1849 of a 32 - pounder being tested for accuracy , killing a gunner . He believed safer , more powerful naval cannon could be designed using more scientific design criteria . Dahlgren guns were designed with a smooth curved shape , equalizing strain and concentrating more weight of metal in the gun breech where the greatest pressure of expanding propellant gases needed to be met to keep the gun from bursting . Because of their rounded contours , Dahlgren guns were nicknamed " soda bottles " , a shape which became their most identifiable characteristic . Dahlgren boat howitzers . During the Mexican - American War the U . S . found itself lacking in light guns that could be fired from ships ’ boats and landed to be used as light artillery in support of landing parties . Light artillery borrowed from the army proved unsatisfactory . In 1849 , then Lieutenant , Dahlgren began to design a family of smoothbore muzzle loading boat howitzer s that could be mounted in ships ’ launches and cutters as well as being mounted onto field carriages . The first boat howitzers to be designed were a light 12 - pounder , a heavy 12 - pounder ( originally designated a “ medium ” ) , and a 24 - pounder . Later a lighter 12 - pounder ( the “ small ” ) and a rifled 12 - pounder heavy howitzer were introduced . All of the boat howitzers were very similar in design , cast in bronze , with a mounting lug or loop on the bottom of the barrel instead of trunnion s , and an elevating screw running through the cascabel . Having the single mounting lug expedited moving the howitzer from the launch to field carriage and back . In naval service the boat howitzers had gun crews of 10 in the boat and 11 ashore . The field carriage was made of wrought iron . No limber was used in naval service , but two ammunition boxes ( each containing nine rounds ) could be lashed to the axle of the field carriage . Members of the gun crew also carried a single round in an ammunition pouch . The smoothbore boat howitzers fired shell , shrapnel , and canister . The rifled 12 - pounder fired shot and shell . Percussion primers were used in naval service , but the howitzers could also use friction primers obtained from the army . The small and the light 12 - pounder boat howitzers were not popular . The heavy 12 - pounder howitzers were most popular at their intended jobs , while the 24 - pounder boat howitzer were found to serve excellently as primary and secondary armaments on river gunboats and similar small vessels . Some 24 - pounder boat howitzers were apparently rifled , but some contemporary accounts confuse rifled 24 - pounder boat howitzers and the 20 - pounder rifles ( discussed below ) Army use of boat howitzers . Aside from use in naval service , boat howitzers saw service with the land forces as well . The boat howitzers were occasionally used in artillery batteries , but were more often used in infantry units , in a role that would later be called infantry support gun s . At First Bull Run , Company I of the 71st Regiment , NY National Guard brought two boat howitzers with them . The unit had trained on boat howitzers while deployed at Washington D . C . , and when called to Bull Run , brought two of them along . When the regiment retreated they left the howitzers behind for the Confederate forces to capture . During the Antietam campaign , the 9th NY Infantry ( Hawkins ' Zouaves ) , Company K ( Whiting ' s Battery ) employed five Dahlgren boat howitzers ( two rifled , two smoothbore , and one of indeterminate type ) . The howitzers fired on Confederate skirmishers at Snavely ' s Ford and suppressed them . The Confederate Grimes ' ( Portsmouth ) Battery had two smoothbore Dahlgren boat howitzers , with which they fought near Piper ' s Stone Barn . The boat howitzers appeared to be popular — when Grimes ' battery was forced to turn in one of its guns , it chose to turn in a 3 - inch Ordnance Rifle rather than one of its boat howitzers . The 1st Regiment , New York Marine Artillery also armed themselves with boat howitzers , using them for their designed use of amphibious expeditions . The unit participated in 16 raids along the North Carolina coast employing their boat howitzers . The New York Marine Artillery was issued twelve 12 - pounder rifled boat howitzers made by Norman Wiard out of semi - steel , a low - carbon iron alloy . Other than the material used , the Wiard boat howitzers were identical to the Dahlgren 12 - pounder rifled boat howitzers . The Wiard howitzers were not made in large numbers . Boat howitzers were used in the western theaters also . The Indiana Brigade used a Dahlgren boat howitzer in fighting near Grand Prairie , Arkansas on July 5 , 1862 . . While boat howitzers were never commonly used by either army , by the end of the war their use by land forces was very rare . Dahlgren shell guns . Throughout the 18th and early 19th Century , the primary ship to ship weapon were muzzle loading smoothbore broadside guns firing solid shot modestly short distances . This all changed when the French Navy adopted a design of Col . Henri - Joseph Paixhans for a shell gun ( canon - obusier ) of 22 cm ( 8 . 7 - inch ) capable of throwing a 59 lb . shell in a reasonably flat trajectory . The U . S . Navy followed suit adopting the 8 - inch , 63 cwt . Paixhans - style shell gun in 1841 . Dahlgren was determined to design a new generation of shell gun that would be capable of firing explosive shells at higher velocity and greater range . They would also have the capacity to effectively fire solid shot . The ability to fire solid shot would become increasingly important as armored warships appeared on the scene : All of the Dahlgren shell guns were cast iron columbiad s , had a distinctive soda bottle shape and all but two had an elevating screw running through the cascabel . Although some Dahlgren shell guns were tested to failure , no Dahlgren shell gun burst during service , a notable distinction for the time . Dahlgren shell guns were capable of firing shot , shell , shrapnel , canister , and ( with the exception of the XV - inch shell gun ) grape - shot . Specific shell and related guns . 32 - pounder . 32 - pounder gun of 27 cwt . M . 1855 : Little is known about this gun . Few were believed to been produced . The U . S . Navy had several different models of 32 - pdrs , which are hard to differentiate in records . 32 - pounders were the primary armaments of older ships like USS " Cumberland " ( commissioned 1842 ) ( which was sunk by CSS " Virginia " ) and USS " Congress " ( commissioned 1842 ) ( which struck its colors to the CSS " Virginia " ) . Later ships were armed with mixtures of shell guns most of which were designed by Dahlgren . The 32 - pounders were still useful in providing primary or secondary armament to smaller ships and river gunboats . While earlier 32 - pounders would have primarily fired solid shot , and these newer guns were called " shot guns " these newer guns could also fire shell . The 32 - pounder gun of 27 cwt . had a crew of 6 and a powder - boy . 32 - pounder gun of 4500 pounds and VIII - inch Dahlgren Shell Gun : 383 of the 32 - pounders and 355 of the VIII - inch Dahlgren were cast by Alger , Builders , Fort Pitt Foundry , and Seyfert , McManus & Co . between 1864 and 1867 . The 32 - pounder had a crew of 10 and a “ powder - boy ” while the VIII - inch had a crew of 12 and a “ powder - boy . ” Some have argued that these guns are not Dahlgren designs , pointing out that while the guns generally resemble his designs , these guns used an old - style breeching jaws instead of the breech loop found on other Dahlgrens and that there is no elevating screw running through the cascabel . It is also asserted that the guns would have to be elevated by quoins . This is not accurate , particularly for the VIII - inch Dahlgren , as a new iron carriage with an elevating screw beneath the breech of the gun was developed for VIII - inch and other carriages with breech elevating screws were also used . It is also argued that the bores were too small for their late introduction and very few saw service during or after the American Civil War . These guns would most likely have been intended for small riverine and estuarine gunboats , which the Navy scrapped as quickly as possible after the war . The documentary evidence also supports a conclusion that these two guns should be considered to be Dahlgen designs . In Mrs . Dahlgren ’ s petition to the national government for compensation for the use of Admiral Dahlgren ' s inventions , both the 32 - pounder gun of 4500 pounds and VIII - inch shell gun are specifically described as designs of Admiral Dahlgren . Also in February 1867 , Cyrus Alger paid a royalty on the Dahlgren patent for production of “ ten 8 - inch guns weighing 64 , 270 , $ 642 . 70 . ” There can be little doubt that both of these guns should be credited as Dahlgren designs . IX - inch . IX - inch Dahlgren shell gun : 1 , 185 guns were cast at Alger , Bellona , Fort Pitt , Seyfert , McManus & Co . , Tredegar , and West Point foundries between 1855 and 1864 . Fort Pitt Foundry also made 16 for the Army in 1861 . The IX - inch Dahlgren was the most popular and versatile of Dahlgren Shell guns made . The IX - guns served as broadside armament on larger ships such as USS " Susquehanna " , which carried 12 IX - inch Dahlgren guns in broadside mounts in addition to her two pivot guns and USS " Powhatan " which carried 10 IX - inch guns in broadside mounts in addition to her 2 XI - inch Dahlgren pivot guns . These broadside guns would normally be mounted on a Marsilly carriage ( see illustration ) . Smaller coastal blockade ships such as and mounted IX - inch Dahlgrens on pivot mounts . IX - inch Dahlgrens were used on several river gunboats such as USS " Essex " and the . If mounted as either a pivot gun or a broadside gun the IX - inch Dahlgren had a crew of 16 and a “ powderman . ” X - inch . X - inch Dahlgren shell gun ( light ) : 10 were cast at Seyfert , McManus & Co . and West Point Foundries between 1855 and 1864 . Pivot mounted on board ships such as , and ( pre - " CSS Virginia " ) with a crew of 20 and a “ powderman . ” X - inch Dahlgren shell gun ( heavy ) : 34 cast between 1862 and 1865 . Designed from the beginning to fire shot against armored ships with heavier powder charges . Mounted on a pivot mount with a crew of 20 and a “ powderman . " XI - inch . XI - inch Dahlgren shell gun : 465 were cast at Alger ; Builders ; Fort Pitt ; Hinkley , Williams & Co . ; Portland Locomotive Works ; Seyfert , McManus & Co . ; Trenton Iron Works ; and West Point foundries between 1856 and 1864 . This is the only Dahlgren gun to have been designed both with and without a muzzle swell . The gun was typically mounted on a pivot or in a turret on a monitor . When mounted in a turret , the crew for an XI - inch Dahlgren was 7 including powdermen . The crew for the gun when mounted on a pivot was 24 men and a “ powderman . ” XI - inch Dahlgrens were carried on " Neosho , Marietta , Casco , Milwaukee , " and ( 1 XI - inch and 1 XV - inch short ) class monitors as well as the original " USS Monitor " . The " USS Kearsarge " , " USS Powhatan " , and many other conventional ships carried XI - inch Dahlgrens on pivot mounts . A few larger river gunboats , such as USS " Tuscumbia " and " USS Indianola " also carried XI - inch Dahlgrens . XIII - inch . XIII - inch Dahlgren shell gun : The XIII - inch Dahlgren was originally intended for " Passaic " class monitors but proved unsuccessful and the XV - inch Dahlgren was used instead . XV - inch . XV - inch Dahlgren shell gun ( short or " “ Passaic ” " ) : 34 were cast by the Fort Pitt Foundry between 1862 and 1864 . The first XV - inch guns ' barrels were so short that the muzzle was inside the monitor ' s turret when the gun was discharged . The resulting blast and fumes in the turret would have made the gun impossible to work . The Navy constructed “ smoke - boxes ” inside the turrets of the monitors equipped with the short XV - inch gun ( see illustration ) , but the presence of the smoke - boxes slowed the rate of fire for the guns . When mounted in a turret , the crew for a XV - inch Dahlgren was 10 including powdermen . Carried on " Passaic " ( 1 XI - inch and 1 XV - inch short ) and early " Canonicus " class monitors . 15 inch Dahlgren guns for the Russian " “ Passaics ” " , the " Uragan " class were produced at the new Aleksandrovsk gun factory in Petrozavodsk in Russian Karelia . XV - inch Dahlgren shell gun ( long or " “ Tecumseh ” " ) : 86 were cast by the Alger , Fort Pitt , and Seyfert , McManus & Co . foundries between 1864 and 1872 . The new XV - inch gun was lengthened 16 inches so that the muzzle was flush with the outside of the turret when fired , eliminating the need for the smoke - box , Carried on later " Canonicus " class monitors . XX - inch . XX - inch Dahlgren shell gun : four were cast by the Fort Pitt Foundry between 1864 and 1867 as part of the original planned armament for USS Puritan . Three of these , named ' Satan ' , ' Lucifer ' and ' Moloch ' were accepted by the U . S . Navy , but saw no service . The fourth gun , named ' Beelzebub ' was sold to Peru , where it became part of the defenses of Callao . Dahlgren shell guns and Rodman casting . The navy ' s demand for 15 - inch guns to defeat the new Confederate ironclads placed Dahlgren in a dilemma . All of his earlier shell guns had been cast solid , then had the bore drilled out — the traditional way to make artillery . Dahlgren ’ s efforts with the XIII - inch shell gun were unsatisfactory and it was not clear that he could solid cast a 15 - inch gun . However 15 - inch guns had been successfully cast using the techniques developed by Thomas Jackson Rodman . Rodman developed a hollow casting method , where the gun was cast around a hollow pipe . As the casting cooled , a smaller pipe was inserted into the first and water was pumped through the small pipe . At the same time hot coals were placed against the outside of the casting . This caused the casting to cool slowly from the inside out . As the outer parts of the casting cooled , they compressed the already cooled inner parts , making a stronger gun . The Bureau of Ordnance ordered that the Dahlgren XV - inch and XX - inch shell guns be cast using the Rodman hollow casting method . This use of Rodman hollow casting with a Dahlgren designed gun led to friction between Dahlgren and the Bureau of Ordnance , as well as some confusion in nomenclature . Table of Dahlgren shell and related guns . Estimated values are indicated by an asterisk . Estimates by , except for the estimate of the overall length of the X - inch ( heavy ) which is based on a bore length of 117 . 75 inches and the estimate of the weight of the XX - inch shell which is based on the weight of the shell for the Columbiad , Seacoast , 20 - inch , Model 1864 . Dahlgren rifled guns . Dahlgren designed several rifled muzzle loading cannon , as well . 20 - pounder rifle : An entirely bronze gun that was popular and was the only Dahlgren rifle ( other than the 12 - pounder boat howitzer ) that continued in service after the American Civil War . Crew of six and a “ powder - boy ” firing a 20 lb . shell in front of 2 lb . of powder it had a range of 1 , 960 yards at a 6 . 5° elevation . 30 - pounder rifle : These guns were iron with bronze trunnions and trunnion bands . They were cast at the Fort Pitt foundry and the Washington Navy Yard . In February 1862 , Dahlgren recommended that the first 13 cast at Fort Pitt be withdrawn because the iron was inferior . One 30 - pounder rifle was mounted on USS " Harriet Lane " . 50 - pounder rifle : These guns were typical Dahlgren rifles — iron with bronze trunnions and trunnion bands . They were apparently a popular design , although by the end of the war it had been supplanted by the 60 - pounder Parrott rifle , which continued in service after the American Civil War . A photograph of Admiral Dahlgren leaning against a 50 - pounder rifle may be found at the beginning of this article . 80 - pounder rifle : The first 80 - pounder was cast at the West Point foundry with trunnions . Subsequent rifles were cast without trunnions and bronze trunnion band and trunnions were added . The gun was initially well received but soon showed a tendency to burst . , a converted Coastal Survey ship armed with 1 IX - inch Dahlgren and 1 80 - pounder Dahlgren rifle was engaged in the bombardment of Roanoke Island in support amphibious landings , when the following entry was made in her log for February 7 , 1862 : “ At 5 : 15 , rifled 80 - pounder aft , loaded with 6 pounds powder and solid Dahlgren shot , 80 pounds , burst in the act of firing into four principal pieces . The gun forward of the trunnions fell on deck . One third of the breech passed over the mastheads and fell clear of the ship on the starboard bow . One struck on port quarter . And the fourth piece , weighing about 1 , 000 pounds , driving through the deck and magazine , bringing up on the keelson , set fire to the ship . Fire promptly extinguished . ” 150 - pounder rifle : The 150 - pounder was a typical Dahlgren rifle with a cast iron barrel and a bronze trunnion band and trunnions . Although the test firing was successful the guns were not placed in service , because Dahlgren doubted the quality of the iron . 12 - inch rifle : In 1864 the Fort Pitt foundry bored 3 XV - inch Dahlgren shell gun blanks , one was finished using the Atwater design , one with the Parrott design , and one with the Rodman approach . The Rodman solid shot weighed 618 to 619 pounds and the Atwater solid shot 416 to 535 pounds . The weights of the Parrott projectiles are not recorded . In 1867 , at Fort Monroe , the guns were tested with charges varying between 35 and 55 pounds until the guns failed . Table of Dahlgren rifled guns . Estimated values are indicated by an asterisk . Estimates by .