Bottom of the Barrel, Part 3: Confederate 13-inch Mortars

Another example of Confederate use of old ordnance comes from the service files of William Richardson Hunt:

The document accounts for the issue of a 13-inch mortar, mortar bed, 12 shells, and 250 fuse plugs in April 1862 for use at Fort Pillow. Hunt sent the mortar to Captain Hugh T. Scott, ordnance officer at the fort.

Now where did the Confederates acquire a 13-inch mortar? In the decades before the Civil War, the Army purchased only one mortar in that caliber for experimental purposes. Series production of the 13-inch Model 1861 Seacoast Mortar began in late 1861. The Federals first used mortars in those calibers, as I’ve mentioned before, in the sieges at Fort Pulaski, Island No. 10, New Orleans, and Yorktown. Fort Pitt Foundry did not sell any to the Confederates. And there are no instances where these brand new mortars fell into Confederate hands before April 1862.

There is one request for 13-inch mortars, sent to Tredegar Foundry in August 1862 (Big Guns, page 14). But these do not match any known castings or entries in the “gun book.” Tredegar did produce mortar beds and 13-inch shells.

More likely the mortar issued to Fort Pillow was an old foreign type. Reports from both sides mention 12- and 13-inch mortars in the Pensacola, Florida forts. Federals used mortars of each caliber in defenses at Fort Pickens (OR, Series I, Volume 1, Serial 1, page 440). An inventory of Confederate ordnance dated April 20, 1861 cites two 13-inch mortars in the forts around Pensacola (OR, Series IV, Volume 1, Serial 127, page 227). And there’s still one there today. These were iron weapons, typical of the British designs between the Revolutionary and Napoleonic period. Bronze 13-inch mortars from the colonial days survive today, and might also account for the Fort Pillow weapon.

The new American Model 1861 mortars out-ranged the old British mortars, but the two types fired essentially the same projectiles. Perhaps Confederate leaders proposed using the 13-inch mortar at Fort Pillow to harass the Federal mortar boats – mortar on mortar counter-fire. Or perhaps the big mortar was there to cover the land approaches. But no records survive to indicate performance of the mortar, if employed at all.

The mortar sent to Fort Pillow is yet another example of what the Confederates found at the bottom of the barrel. The use of a British seacoast mortar (if my deductions are correct) is not as absurd as the bronze mortars seen in Florida or at Island No. 10. Still all were better suited for museums or trophy yards than the battlefield.

Evolution of the Big Mortars: 13-inch Mortars Model 1861, Part 1

Yesterday I discussed the classifications of mortars used in the Civil War period.  Today I’ll focus on the largest of the “heavy” mortars – the 13-inch Model 1861.  Due to employment, this mortar fits into two of those classifications – seacoast and sea.  So let me provide a brief history of the type and some of the particulars (saving details about the ammunition, operations, and service history for later posts).

The Americans used 13-inch caliber mortars in the Revolutionary War.  Among the siege weapons used at Yorktown in 1781 were 13-inch bronze mortars. Along with many other colonial vintage weapons, these soldiered on through the War of 1812.  However in 1818, the caliber failed the cut when an Ordnance Board established the first true system of American artillery.1 On the other hand the Navy retained, at least for contingencies, the 13-inch mortar.  However after the Barbary Wars, the Navy had little need for mortar armed “bomb” vessels.2

During a revision of the artillery system in 1839, the Army reconsidered the 13-inch caliber for seacoast mortars.  The Ordnance Manual of 1850 included specifications for a 13-inch heavy mortar as part of the patterns of 1841.  The pattern called for a weapon 53 inches long, with a 39 inch deep bore (including chamber), that weighed 11,500 pounds.  Range tables credited this mortar with a maximum of 4325 yards firing a 200 pound shell propelled by a 20 pound charge.3  However only one of these were ever produced.  The Army had the second of two on contract bored out to 12-inch caliber instead (credited with a 4625 yard range).4   The Army did not contract for series production of either caliber, leaving these weapons only as experimental types.

Because the Army had standardized the 13-inch caliber, when the Ordnance Board revised the artillery system for 1861, a new pattern of the type emerged.  Indeed all the Army’s mortars received a pattern update.  The chart below provides the particulars of those weapons from 8-inch to 13-inch.5,6

Just as with other “Model 1861” weapons, the 13-inch mortar offered a more refined design.  Internally, matching the evolutions of Rodman’s heavy guns, an elongated hemisphere replaced the traditional sub-caliber chamber used on previous mortars.  The exterior had only functional moldings which help explain how the weapon was served by the crew.

To start with, unlike larger guns, the mortars didn’t have a cascabel or knob.  So on the top of an otherwise clean barrel, the 13-inch mortars had a lifting lug to aid handling.

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Lifting Lug on 13-inch Mortar at Fort McNair

At the breech end, where other artillery types had a knob, the Model 1861 series mortars had elevating lugs.

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Elevating lugs on 13-inch Mortar at Fort McNair

Although design diagrams show lugs inside a raised strip, all surviving examples I’ve seen are exposed as those seen above. In operation, an elevating bar, fed through an “eye” of an elevating post, engaged the lugs.  Much like the system used on the larger Rodman guns.

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Elevating post with retaining bolt (Fort Moultrie)

Each 13-inch mortar had two vents.  Why?

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Vents on 13-inch Mortar at Fort McNair

The dual vent was due to the lack of bouching on these weapons. Per Army specifications, the foundry drilled the left side vent through to the chamber.  But they left the right side vent incomplete stopping one inch from the chamber.  When the left side eroded with use, it was filled with zinc.  At that time the ordnance crews drilled the right side complete.7

To handle the 200 plus pound shells, the carriages included a gibbet (somewhat a double entendre there) or post, as seen on the examples at Charleston’s White Point Gardens.

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13-inch Mortar at White Point Gardens

The markings on 13-inch mortars are at times frustrating.  As per regulation, the registry number, foundry, year of manufacture, weight, and inspector stamps appear on the muzzle.

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Weight Stamp on 13-inch Mortar at Fort Moultrie

As you see in the photo above, those were not scaled out to take advantage of the ample muzzle face.  Often these were only lightly stamped and easily eroded away.  Thus even with several quality photos of mortars like the “Dictator,” historians have trouble identifying specific mortars by registry numbers.

Fort Pitt, the sole manufacturer of the 13-inch mortar, placed the foundry tracking number in raised numbers above the right trunnion.  On many survivors, this is the only easy way to identify a specific weapon.

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Foundry Number of Fort Moultrie's mortar

Then again, even that raised number disappears from some mortars.

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Missing Foundry Number on a Charleston Mortar

Thankfully, the number appears frequently enough to aid identification and interpretation.

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Foundry number 680 at Charleston

Foundry number 680, today at Charleston’s White Point Gardens, was among the first batches of 13-inch mortars from Fort Pitt.  It received registry number 22 and was credited in January 1862.

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13-inch Seacoast Mortar, Fort Pitt #22

Given the early reception of this particular mortar, there’s a high likelihood it saw some action in the spring of 1862 – Island No. 10, Fort Pillow, New Orleans, Fort Pulaski, or Yorktown.

If only the mortar could speak….

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Notes:

  1. Birkhimer, William, Historical Sketch of the Organization, Administration, Material and Tactics of the Artillery, United States Army  (Washington:  James J. Chapman, 1884), Pages 275-279.
  2. Tucker, Spencer, Arming the Fleet: U.S. Navy Ordnance in the Muzzle-loading Era (Annapolis: Naval Institute Press, 1989), pages 107-109, 143.
  3. U.S. War Department, The ordnance manual for the use of officers of the United States Army (Washington: Gideon & Company, 1850), pages 7 and 364.
  4. Edwin Olmstead,  Wayne E. Stark, and Spencer C. Tucker, The Big Guns: Civil War Siege, Seacoast and Naval Cannon (Alexandria Bay, NY: Museum Restoration Service, 1997), Appendix C163, page 261.
  5. Data for the chart assembled from:
    1. U.S. War Department, The ordnance manual for the use of officers of the United States Army (Philadelphia: J.B. Lippincott & Company, 1862), page 18.
    2. Tidball, John C., Manual of Heavy Artillery Service (Washington: J.J. Chapman, 1884), pages 145-166.
    3. Olmstead, et. al., Appendices C118, C146, C257, and C164; Pages 239,  255, 257, and 261.
  6. There is a discrepancy seen between the length of trunnions specified in the Ordnance Manual and those on surviving examples.  Surviving 8- and 10-inch mortars have 3.25 inch lengths, while the 13-inch have 4.5 inch trunnions.
  7. Tidball, page 36.

Mortars That Signaled the Start of the War

Continuing with my discussion of the cannons used at Fort Sumter in April 1861, I turn now to the mortars employed by the Confederates.  One of these weapons signaled the “start” of the war (although I plead ambiguity there).

A drawing in the first volume of Battles and Leaders depicts two mortars on Morris Island from Lieutenant C.R. Homes’ Battery.   (Several published photographic collections credit the original image to the Charleston Historical Society.  If you know of a digital copy, please let me know!)

Mounted on wooden beds, these mortars appear very similar to a surviving mortar on display at Fort Sumter today.

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10-inch Mortar at Fort Sumter

The central band with trunnions, the chase, and the muzzle lip match the shape from the drawing and photograph.  Over the trunnions are the stamps “HF // No. 4 // 34 – 1 – 25.”

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Breech and Top of 10-inch Mortar

The initials HF are associated with several early cannon-makers, but in this case points to Henry Foxall, the first owner of Columbia Foundry in Washington, D.C.  A report from 1807 indicates Columbia was producing forty 10-inch mortars to complement eighteen already on hand.  As such this mortar is tentatively considered “Seacoast Mortar of 1807 Pattern.”

The three numbers in the stampings indicate the hundredweight measurements, which translate to 3861 pounds. The mortar at Fort Sumter is the sole survivor of its kind. It measures 45 inches in length. and has 10 inch diameter trunnions.  The 10-inch seacoast mortar fired a 90-pound shell with a 10-pound powder charge to a maximum range of 4,250 yards.

Two similar surviving weapons (one of which is at West Point) are smaller in length, at 31 inches.  These are tentatively identified as “Siege and Garrison Mortars of 1807 Pattern.”  And these differ externally, having trunnions set further back on the central band.  Given that distinguishing characteristic, likely the mortars depicted at Morris Island were of the seacoast type.

Correspondence and witness accounts from Charleston in 1861 allude to a lot of Tredegar mortars.  Although Tredegar was not a prolific source for Federal mortars, the firm must have produced some for state requirements.  Perhaps Tredegar used the same or similar pattern from the early days of the 19th century.

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Muzzle of 10-inch Seacoast Mortar

Looking at the muzzle, I would be remiss not mentioning the shot that “almost could have been” the start of the Civil War (a story my friend Robert Moore is fond of).  On March 8, 1861, some of the South Carolina volunteers on Morris Island were in the middle of drill with blank cartridges.  At some point in the process, the crew loaded a shell and let fly! The shell bounced off the fort causing little harm.  A Confederate officer proceeded to Fort Sumter under a flag of truce to explain the miss-fire and all were satisfied.  (see OR, Series I, Volume 1, Serial 1, pages 192 and 273.)

On April 6, Major Robert Anderson, commanding at Fort Sumter, noted with alarm more Confederate mortar drills.  In that case a mortar battery at Mount Pleasant, on the other side of the bay, fired practice shells too close to the Federal garrison.  Again, the Confederates offered an apology and redirected their practice fires.  (see OR, Series I, Volume 1, Serial 1, pages 246-7.)  But with these two incidents – what today we’d cite as “fire discipline” related – we have episodes which might have sparked the war before the Confederates had completed their preparations… had the Federals the presence of mind to “practice” back at them.

Of course the presence of mortars, such as that pictured above, on Morris Island does not help positive identification of model which fired from Fort Johnson to start the war.

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First Shot of the War Marker

A Model 1840 for both seacoast and siege mortars in the 10-inch caliber also existed, and their presence at Charleston may not be ruled out.  But I would point out the mortars around the harbor were not among the weapons taken over by South Carolina in December 1860, and presumably were part of the state’s militia arsenals.  Such lends weight to uniform batteries of the older types, but not with much certainty.

Regardless of the exact type, at around 4:30 a.m. on April 12, 1861, Captain George S. James fired (or at least gave the order to fire) a 10-inch shell in the direction of Fort Sumter.  And unlike the two previous incidents, this shot was not for practice.

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View of Fort Sumter from Fort Johnson

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

Ordnance Manual for Use of the Officers of the United States Army.  Philadelphia: J.B. Lippincott, 1862. (Google Books copy)

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.