8-inch Siege Howitzers – Model 1861

While the 8-inch Siege Howitzer Model 1841 met specifications, twenty years worth of advances in metallurgy necessitated a redesign.  The change, of course, was not isolated to the heavy howitzer, but rather indicative of overall trends culminating with standards set forward in a new system of artillery formally established in 1861 and published in the Ordnance Manual the following year.   Arguably representing the pinnacle of muzzle loading artillery technology, the system featured designs with clean lines and embraced new construction techniques (oh, and of course standardized rifled gun types, but that is a sidebar to this story).  In complying with the new regulations, three design changes sat the siege howitzer of 1861 apart from the preceding Model of 1841:   smooth exterior lines, redesigned chamber, and hollow-core casting.

8-in. Howitzer Plan from Manual

The Ordnance Regulations of 1861 specified a form with no moldings.  The knob connected to the breech with a short neck, without fillet.  The rimbases blended into the barrel almost without notice.  The only right angle in the form was where trunnions met the rimbases.

Bore and Chamber of 8-in Model 1861

The regulations also specified the use of “semi-ellipsoid” shaped chambers.  From perhaps ancient times, cannon makers assumed a sub-caliber chamber served to focus the force of the charge.  Such were used on howitzers and mortars in particular to squeeze additional performance from a reduced charges, compared to guns of the same caliber.  (A good example of this line of thinking appears in John Muller’s A Treatise of Artillery from the late 18th Century, on page 20 of the introduction.)   Empirical tests by both Army and Navy in the 1840s and 50s determined this to be false.   While offering no ballistic advantage, sub-caliber chambers introduced a complication in the boring and finishing process.  In operation, crews found the neck and bottom of chambers difficult to keep clear.  And in the larger caliber weapons such as the 8-inch howitzers,  the thick wooden sabot required for seating the projectile presented a danger to friendly forces in front of the weapon.  (Such danger was referenced in the instruction manuals used at West Point at the time.)  The “semi-ellipsoid,” or what we modern readers would call an extended hemisphere, introduced in 1861 alleviated the need for special boring, eased field maintenance, and eliminated the need for the sabot.

8in Siege Howitzer Model 1861 - Petersburg

The last important change presented for Model 1861 was not visible.  Advances during the 1840s and 50s in the study of iron’s properties allowed improvements in the reliability of cannons.  One major advance entailed a better understanding of the behavior of iron alloys at a molecular, or at least crystalline, level.  This lead to better selection of iron mixed with other materials, and the outright rejection of hot blast furnace smelting habits.  Regarding the actual production of the weapon, Captain Thomas J. Rodman developed, through testing heavy caliber columbiad weapons in the 1850s, a method of casting the weapon with a hollow core for the bore.  Once cast, the weapon was cooled with the use of a water filled tube placed in the bore.  The process might take days to complete, but in effect cooled the weapon from the inside out.  The result was a very durable cannon.  This hollow-core, water-cooled process was explained in detail by John Gibbon in the Artillerist’s Manual of 1860.    Gun foundries used this technique in casting of the 8-inch howitzers of the new model.   This technique also allowed the reduction of the weapon’s overall weight.

Comparison of Heavy Field, Siege, and Garrison Howitzers

In spite of the design changes, the new howitzer presented few differences from an operational standpoint.  The 8-inch Howitzer Model 1861 retained the same trunnion dimensions and rimbase spacing as the older model, and was used on the same 24-pdr Siege Gun Carriage.   While not stated directly, the new pattern likely required the same quoin arrangement for elevation.   As the Model 1861 used the same weight of powder to propel the same size projectile off the same length of bore, the new weapon performed as the old with regard to range.  And the new 8-inch howitzer used the same types of ammunition, sans sabot of course.

Production of the new model began in 1862, when the Fort Pitt Foundry in Pittsburgh, Pennsylvania discontinued casting the Model 1841.  Fort Pitt delivered 84 of the Model 1861, with the last credited in October 1864.  Cyrus Alger of Boston, Massachusetts began deliveries in mid-1863.  The Army accepted the last of 87 from Alger in the summer of 1865.    All told 171 examples from two vendors.

Photographic evidence places some of these weapons in the Washington defenses:

Interior of Fort Carroll, Maryland

The second and third artillery pieces from the camera have the distinctive profile of the 8-inch Model 1861.  (The closest gun is likely a 32-pdr seacoast gun.)

At least a few saw action at Petersburg.

Artillery at Broadway Landing, Appomattox River, Virginia

Three 8-inch Howitzers Model 1861 stand on the back row, third, forth, and fifth from the left.   It is not clear if this artillery park outside Petersburg contains strictly weapons captured from the Confederates or a mix with weapons used by Federals during the siege.  But in the foreground is a Confederate iron Coehorn mortar.  And the Parrott rifle on the front rank to the far right has a distinctive “Confederate” bevel on the band.  The piece in the foreground on a damaged carriage is a 32-pdr Navy gun, a type more likely found in the Confederate siege park.   While I would not consider this proof that some 8-inch Howitzers Model 1861 were captured by the Confederates and put to use, pending more information about the photograph, the speculation is on the table.

Mostly, like the Model 1841 type, the Model 1861 howitzers spent the war quietly defending strategic locations.  Post war, the Model 1861 remained in the Army inventory until at least the 1880s.

Just over eighty of the Model 1861 howitzers survive today, mostly in memorial displays.  The only two that I know of currently displayed in the National Parks are examples on the artillery display rails at Petersburg.  Both are from Fort Pitt Foundry, sequential registry numbers 6 and 7 from 1862.  One is pictured at the top of this post, and the other here:

Artillery Display at Petersburg

A survivor with a rather eventful post-war history is a memorial in Glen Ellen, California.  Fort Pitt registry number 37 is known as the “Glen Ellen Cannon.”  The howitzer was a gift to the community in 1905 and stood outside a lodge for many years.  In 1992, a new owner of the lodge attempted to sell the howitzer to a collector – “…galvanized by the imminent threat of having the town cannon … sold to an East Coast collector. Citizens chained themselves to the historic relic in protest.”

For those who wonder what one of these big howitzers looked and sounded like in action, Paulson Brothers Ordnance Corporation makes reproduction 8-inch Model 1861.  And here’s a taste of the howitzer on the range:

Look at that recoil!


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.

Muller, John.  A Treatise of Artillery.  Reprint of the 1780 edition.  Alexandria Bay, NY: Museum Restoration Service, 1977.

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.

Published by Craig Swain

"Historical marker hunter" and Civil War enthusiast.

2 thoughts on “8-inch Siege Howitzers – Model 1861

  1. Could anyone shed light on a five-pointed star mark stamped onto the right side of muzzle face of an M1861 8-inch siege howitzer? Any idea what that signifies? Thanks.

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