page_title: Dahlgren gun
section_title: Dahlgren boat howitzers
hierarchical_section_title: Dahlgren gun / Dahlgren boat howitzers
caption_attribution_description: Line engraving of Dahlgren Boat Howitzer mounted on a Field Carriage.
context_page_description: Dahlgren guns were muzzle-loading naval artillery designed by Rear Admiral John A. Dahlgren USN, 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 a 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.
context_section_description: 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 (Ripley 1984, p. 87). Light artillery borrowed from the army proved unsatisfactory. In 1849, then lieutenant, Dahlgren began to design a family of smoothbore muzzle-loading boat howitzers 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 trunnions, 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)
caption: Dahlgren boat howitzer mounted on field carriage
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