24-pdr Flank Howitzers

The 24-pdr Siege and Garrison Howitzer was the caliber set companion to the 24-pdr Field Howitzer.  Cast of iron and weighing more, the Army used the siege and garrison weapon largely in the “garrison” part of that description.  Conceptually the weapon sprang from a need to cover blind approaches and moats around the masonry fortifications of the day – the flanks of the walls.  Such employment gave the weapon the common name “Flank Howitzer” which I prefer.

Early seacoast fortifications used a mixture of howitzers and even naval carronades to cover the landward approaches. As construction of the “third series” forts began in earnest, the Army required a replacement for the old weapons.

Carronade on Flank Carriage - Fort Morgan, Alabama

Between 1841 and 1844, depending on which regulation is read, the Ordnance Department standardized the 24-pdr howitzer for these requirements.  The Ordnance Manual of 1850 listed the “24-pdr Siege and Garrison Howitzer  Model of 1841″ with the standard 5.82-inch bore for a 24-pdr.   The weapon’s chamber, at 4.62-inch diameter to a depth of 4.75 inches, complied with convention being one step down from the bore size (in this case a 12-pdr caliber diameter).  The other particulars of note are displayed below in comparison to the 24-pdr Field Howitzer, 32-pdr Field Howitzer, and two models of the 8-inch Siege Howitzer.

Of note, the trunnion diameter and rimbase spacing (at 12.8 inches nearly two inches shorter than a 12-pdr Siege Gun) did not allow the howitzer to use any of the standard siege gun carriages.  Also the preponderance (the excess weight of the rear of the piece) was 70 pounds – half that of the 24-pdr Field Howitzer, and even lighter than the 12-pdr Field Howitzer (which had a 90 pound preponderance).   These last two details indicate the weapon was designed for use on a specific mounting within fortifications, in cramped quarters, where rapid training and elevation were called for.   The 1851 Instruction for Heavy Artillery offered a plan for just such a Flank Casemate Carriage:

24-pdr Howitzer on Flank Casemate Carriage

The rails attached to a front pivot point, and traversed with a set of wheels running on a metal race at the rear.  The Howitzer and top carriage sat on brass rollers, with eccentric roller at the rear to reduce travel due to recoil.  A reproduction (possibly with original fittings) of such a carriage is displayed in the Caponiere at Fort Washington in Maryland.

Flank Howitzer on Carriage - Fort Washington

The top carriage basically a cradle holding the howitzer, supported by the wheels and rollers.  Note the eccentric roller at the bottom of the view below:

Top Carriage and Howitzer

The howitzer itself had a plain appearance, with breech, chase, and muzzle rings as its only adornments.  Unlike the 24-pdr bronze field howitzer, the iron flank howitzer had no handles, and the reinforce was flush over the chamber.  Early batches (from Cyrus Alger & Company of Boston) placed the chase ring 7 inches from the muzzle.  All of the later examples had the chase ring 5.5 inches from the muzzle.  Otherwise the weapons exhibited only variations with markings.

24-pdr Flank Howitzer - Fort Washington

At Fort Pulaski, Georgia, the defensive arrangements included flank howitzers covering the interior angles of the inland side of the fort.  In the view below, the port for the flank howitzer is at the interior corner of the bastion, just above the whitish patch of bricks.  This allowed the howitzer to cover the moat with shell, or if the target were close as the photographer in this view, canister.

Flank Howitzer Port - Fort Pulaski

Tactically, the flank howitzer offered no advantage in range over the bronze field piece, and of course was heavier.  However, it could withstand years of use, resisting bore erosion better.  While the durability was certainly a design consideration, particularly with an eye to prolonged siege operations, the weapons were never called on for such.  Another advantage, since the flank howitzer operated in a static role the crew was reduced to only three men.

The 24-pdr Flank Howitzer remained in production from 1845 to 1864.   Cyrus Alger delivered 350 examples.  Fort Pitt Foundry in Pittsburgh contributed twenty-two; and West Point Foundry added another twenty-six in pre-war contracts.  Tredegar Foundry in Richmond delivered twenty-five before the war.  Similarly, Bellona Foundry outside Richmond, Virginia delivered four before the Civil War, and likely a few for the Confederacy after the war broke out.  Mt. Vernon Iron Works of Ohio provided fifty (the only cannon received from that source) in 1863-64.  Seyfert, McManus & Co, also known as Scott Foundry, of Reading, Pennsylvania added an even hundred, mostly in 1864.  All told the Army received 577 24-pdr Flank Howitzers from these seven sources, making it one of the most widely produced smoothbore types in the American Army.

The type’s service record was, however, uneventful for the most part.  Not designed for field issue, the flank howitzers remained at coastal fortifications or complemented new land-locked fortifications in the rear areas.  Dozens supported the defensive works around Washington, D.C. and likely a few found their way to defenses around key cities in the Western Theater.  But for the most part, there just was not a demand for these heavy iron howitzers from the active armies.  The Confederates also used the type, and I plan to cover those instances in a separate post.

Perhaps due to the limited use, a high number of these weapons survived the war to grace town squares and parks today.  Nearly 250 all told grace parks, cemeteries, town squares, museums, memorials, and coastal forts today.   One example stands on display outside the Museum in Boonesboro, Maryland, just north of Antietam.

Alger No. 52 - Cast in 1846

In other cases, the flank howitzers almost hide from visitors.  Anyone who has visited Gettysburg has probably walked passed two examples, yet few notice them.

High Water Mark Monument at Gettysburg

Note the breech of a flank howitzer to the lower right near the foundation for the monument.

Breech of Flank Howitzer

Buried muzzle down, two flank howitzers mark the corners of the monument.  Their manufacture, registry numbers, or other particulars are unknown, and likely the markings have eroded with many years of burial.  Perhaps fitting, given the type’s history, that two 24-pdr Flank Howitzers are granted a somewhat inglorious place, yet at a critical point, on the Gettysburg battlefield.

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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.