Information about Ordnance


By Bill Utley, Maritime Heritage Branch, ASV (posted December 13, 2020)


For four hundred years, smoothbore artillery dominated the war at sea. But smoothbore weapons were problematic.  Material, construction methods, ammunition, and powder quality limited their range, reliability, and accuracy. Smoothbore weapons required the ammunition to be round, and significantly smaller than the bore diameter to account for imprecise manufacturing tolerances of both the artillery piece and the ammunition, and to account for fouling from unburned powder. In naval terms, the fact that guns and carronades were the primary armament meant that shells could not be used, thus eliminating casualty-producing explosive rounds that could also prove devastating against wooden warships.

The Shell Gun

In the early 1822, French General Henri-Joseph Paixhan advocated the development of a gun that would fire a shell on a flat trajectory, and this eventually developed into the Paixhan gun. Up to this time, shells were fired on loping trajectories designed to go over obstacles like walls and berms. Adopted by the French Navy in 1841, the Paixhan gun was the first naval artillery designed specifically to fire shell. The two basic problems with this new gun was its short range and the fact that it could only fire shell, not shot.

All the European western naval powers adopted shell gun technology, as well as the US Navy. In the 1840s the US Navy adopted an 8-inch and 10-inch Paixhan shell. In 1849, John A. Dahlgren developed an improvement to the shell gun, and his ultimate design was used in the United States in the 1850s and 1860s.  All the Dahlgren shell guns were cast-iron Colombiads, with a very distinct bottle shape. The design proved to be very reliable as none burst during use, unusual for cast-iron guns. Dahlgren’s new guns solved the problems of range and ammunition type. His guns could fire at considerably longer ranges and could fire both shell and shot.

Dahlgren guns were very large – a 32-pdr, and IX to XX-inch guns. These are not the type of artillery piece that would be used on a land battlefield, but they were used in land fortifications as well as on board ships. However, it is unlikely that any land excavation would come across one of these. But encountering one in the water is a different matter.

IX Dahlgren Shell Gun on Display at Gaylord, Michigan

Archaeologist John Haynes, at the time the Base archeologist for Quantico MCB, ran across an obscure historical reference to an incident of the Confederate forces sinking a barge with two guns onboard in the Potomac River on 8-9 May 1862. It is rare when such references prove to be valid, but since survey work was already being undertaken in Quantico Creek, it was decided to give the area a cursory look. On 9 April 2011, Dr. Gordon Watts and Joshua Daniel, working with the Institute of Maritime History (IMH) on the Quantico Creek side-scan survey, ran a series of search patterns in Maryland waters off the mouth of Quantico Creek. Within ten minutes of starting, a target was located that looked like it could be a canal boat. While there was a great deal of debris showing, it was not possible to tell if there were guns on board, however the site matched the brief historical reference. The site was duly registered with the State of Maryland.

Survey Image (Side Scan Sonar) – David Howe (IMH), 2016

It was not until May and October of 2016 that it was possible to dive the target, which lies at about 50 feet in black water. In May IMH divers found one IX-inch Dahlgren shell gun, mostly buried in sediment. In October a second IX Dahlgren was discovered, again by IMH divers, including the current MHT Chapter President. One lies inboard on the starboard side and the other off the wreck to the port side. The rest of the site is unexplored to date, but it is possible that ammunition for the guns is also on board.

The shell gun is a little-appreciated revolution in naval warfare. The impact of large explosive shells on wooden hulls was devastating. Shell guns were one of the factors that made wooden warships obsolete and would eventually lead to the more effective use of naval artillery for amphibious operations.

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