Dahlgren 12-pdr Small Boat Howitzer

The rarest of Admiral John Dahlgren’s boat howitzers is the smallest 12-pdr small smoothbore of the “family.”   One of only seven surviving examples is on display at the National Museum of the Marine Corps.

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12-pdr Dahlgren Boat Howitzer, Small

In fine USMC tradition that would make the Gunny smile, the boat howitzer shines like the well polished buttons on a dress jacket.

I briefly wrote about this model in a look at Dahlgren’s boat howitzer system last year.   The chart below summarizes the members of the “family” with the small howitzer listed on the fourth data column from the left:

Dahlgren Boat Howitzer "Family" (Click to Enlarge)

At 300 pounds, the Small Boat Howitzer was the lightest of its kind in the Navy (although the Army’s mountain howitzer weighed 100 pounds less).   In terms of external dimensions, the small howitzer was simply a down-size version of the larger 12-pdrs.  But the 12-pdr Small retained the same chamber size, and thus used the same ammunition, as the larger howitzers.  Although using the same projectiles, the Small Howitzer most likely used a reduced powder charge at about half a pound.

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Bore of 12-pdr Dahlgren, Small

Generally, the small version matches the form of the Heavy Howitzer detailed in an earlier post.  The Small Howitzer on display has a restored lockpiece and rear sight.

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Markings and Breech of 12-pdr Small

The layout of the display prevents close examination of the breech and details of the markings.  But just to the left of the lockpiece on the breech is the rear sight.  Not visible (if there at all) is the lug for the front sight.

The museum’s howitzer sits upon an original boat howitzer carriage.  On the shorter barreled Small Boat Howitzer, the underloop where the carriage attached was closer to the muzzle – 21 1/3 inches, against 26 1/2 for the Light Howitzer, and 31 1/4 for the Heavy Howitzer.  Preponderance of the Light Howitzer was 25 pounds.

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Profile and Carriage of the Small Howitzer

On paper, the Small Boat Howitzers offered only a small weight advantage over the others in the system.  With so few produced, the 130 pound difference from the Light Boat Howitzer apparently did not impress naval officers.   After the first production batches between 1848 and 1858, totaling 12 pieces, the Navy Yard ceased making 12-pdr Small Howitzers.  Meanwhile the Light and Heavy Boat Howitzers remained in production.

In 1864, the Navy Yard resumed production with an additional eleven Small Boat Howitzers.  This completed the known deliveries of the type, with a total of 23 on record.  The howitzer on display at the museum is registry number 19.  Sources indicate this howitzer served on the monitor USS Sangamon.

The late production year and presence on a monitor may offer clues about the Small Howitzer’s service.  Perhaps service on the cramped monitors called for a howitzer of smaller dimensions.

Regardless, number 19 in the production series of Small Boat Howitzers, an example of a rare artillery type, provides yet another reason for the Civil War enthusiast to visit the National Museum of the Marine Corps.

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Aside from on site notes and links provided above, sources consulted for this post were:

Hazlett, James C., Edwin Olmstead, and M. Hume Parks. Field Artillery Weapons of the Civil War, Revised Edition. Urbana and Chicago: University of Illinois Press, 2004.

Olmstead, Edwin, Wayne E. Stark, and Spencer C. Tucker. The Big Guns: Civil War Siege, Seacoast and Naval Cannon. Alexandria Bay, NY: Museum Restoration Service, 1997.

Ripley, Warren. Artillery and Ammunition of the Civil War, 4th Edition. Charleston, S.C.: The Battery Press, 1984.

Tucker, Spencer.  Arming the Fleet:  U.S. Navy Ordnance in the Muzzle-Loading Era.  Annapolis, Maryland:  Naval Institute Press, 1989.

Published by Craig Swain

"Historical marker hunter" and Civil War enthusiast.

2 thoughts on “Dahlgren 12-pdr Small Boat Howitzer

  1. Craig, nice writeup. You wrote: “But the 12-pdr Small retained the same chamber size, and thus used the same ammunition, as the larger howitzers.”
    The fixed round of ammunition for each of the three sizes of boat howitzers was different since the powder charge for each was different. The medium 12-pounder had a powder charge of one pound; the light model had a powder charge of 0.625 pounds. I don’t know the precise powder charge used for the small howitzer but I’d guess it was about 0.5 pounds. The charge data is given in Warren Ripley’s “ARTILLERY AND AMMUNITON OF THE CIVIL WAR” pp. 369 under “”Dahlgrens and Shellguns Chapter V.”

    1. John, I’ve found several conflicts in published sources. Ripley’s work, as groundbreaking as it was, missed some details. Dahlgren’s 1858 “Boat Armament” and the Ordnance Instructions of 1865 also offer discrepancies. I mentioned those in an earlier post:

      “One discrepancy arises when comparing service charges listed in the Ordnance Instructions against Dahlgren’s notes and physical dimensions of the boat howitzers. The instructions note two pound charges for the 24-pdr smoothbore and 20-pdr rifle. The 12-pdr heavy and 12-pdr rifle used one pound service charges. But, although the 12-pdr medium and the 2-pdr small featured the same chamber dimensions, the Ordnance Instructions list 0.625 pound service charges. Such loading would either require a special sabot, which is not noted in any instructions, or leave an unacceptable air gap between the charge and projectile.”

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