The Dahlgren Boat Howitzer

Detail of the elevating screw and wheel at the end of the carriage of the 12-pdr. Dalghren boat howitzer. [George Loin as Cot lection)

Detail of the elevating screw and wheel at the end of the carriage of the 12-pdr. Dalghren boat howitzer. [George Loin as Cot lection)

Mexican Artillery
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During the Mexican War, the navy took part in a number of landing expeditions, and learned that it needed field artillery of its own. Admiral John Dahlgren, a leading authority on naval artillery, designed a series of boät howitzers that were accepted as the standard L'.S. Navy weapon a decade before the Civil War.

fliese were guns with a bronze tube and a loop under the barrel tn secure it either to a field or boat carriage. They were all marked by a lack of a muzzle swell and were available in several sizes, although the 12 11). shell or shot was common to many of them. The first version had a 4.62-in. bore and weighed 430 llj. by itself and 000 lb. on its special wrought iron carriage.

The medium howitzer had the same bore but weighed 760 lb., or 1,200 lb on its carriage and was designed for use on frigates. Its range at five degrees was 1,150 yards with case, and 1,085 yards with shell. This was the most popular of this series of cannon.

A lighter version was adopted that weighed 300 Ih., while another standard 12-pdr. with a 3.4-in. bore and weighing 880 lb. was also adopted for use on sloops. A liglii 12-pdr. weighing 300 lb and a rifled bronze 12 pdr. weighing 880 lb were also made during the war. A 20-pdr. with a 4-in, bore and weighing 1,340 lb. was also adopted. During the war a number of rifled 20-pdrs, weighing 1,340 lb. were acquired by the Navy.

The boat howitzer was designed to be mounted on the bow of a launch to fire on an enemy as the

Howitzers Gettysburg

The U.S. Navy Dnhtgren boat howitzer mounted on its all-metal field carriage. (Bureau of Ordnance, Ordnance Instructions, 1666)

boat was making for land. Once the boat hit the shore, a crew of eight to ten men would mount it on its field carriage, an operation that took under four minutes. The weapon was tlien ready for use in ground-fire support. The carriage came with two ammunition boxes lashed to it, while each crew member also carried two rounds of ammunition in a leather pouch. The weapon was landed with a total of 72 rounds of ammunition which was considered more than enough for the typical landing.

The firing rate was eight times a minute —and up to ten times a minute in action - on the carriage, and five times a minute when mounted in the boat. All ammunition was fixed, and the crew had a choice of shell, shrapnel or spherical case, and canister. Powder charges were 1 lb. for the 12-pdr. and 0.625 lb. for the light 12-pounder. The 24-pdr, used a charge of 2 lb., which gave it a range of 1,270 yards for shell and 1 ,308 yards for shrapnel at five degrees elevation.

The navy acquired 456 medium 12-pdr., 177 light 12-pdr., 23 small 12-pdr., '124 rifled bronze 12-pdr., and seven steel 12-pdr. howitzers {which weighed 790 lb.) during the Civil War in addition to 100 rifled 20-pdrs. and 1,009 24-pdr, boat, howitzers. They had all originally been made by the Washington Navy Yard, but demand forced contracts to go to the private companies Ames and Alger. Due to their unpopularity, the navy ceased acquisition of the small and light boat howitzers early in the war.

Although strictlv made for U.S. Navy use, a number of these weapons ended up in army batteries on both sides. At Amietam, for example, they formed part of the ordnance of both Battery K, 9th New York Light Artillery, and Grime's Virginia Battery of the Army of Northern Virginia. They were so popular with the men of Grime's Battery, which was formed in the naval town of Portsmouth, Virginia, that when they were forced to give up one weapon in the overall reorganization, they surrendered a 3-in. Ordnatlce Rille rather than the boat howitzer.

The U.S. Navy Dnhtgren boat howitzer mounted on its all-metal field carriage. (Bureau of Ordnance, Ordnance Instructions, 1666)

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