Dahlgren on shrapnel (case shot): “… even a tolerable approximation … not likely to be undervalued…”

As I’ve opened the ball here, I feel bound to continue the discussion about the practice of case shot… and in particular how this was related to those training to man the guns.  Let me say again for emphasis – the conundrum here is that very little is offered in the manuals (US manuals, but if we want that extends across to the British manuals of the period), yet the type of projectile was seen as a vital component in the ammunition boxes. Specifically, we do not see specific instructions, firing tables, or other such details offered in the texts available to new artillery officers.  I would contend in the context of 1861, with hundreds of volunteer officers grasping guidons as brand-new battery commanders, what was in those manuals was of extreme importance.  And all this in light of experiments and tests in which some very good minds determined shrapnel / case shot should not be handled simply as any old shell.

I mentioned John Dahlgren as one of those looking the performance of shrapnel.  So let us turn to his 1852 “A System of Boat Armament in the United States Navy.”  Now keep in mind that work was more so a justification for the concepts incorporated in the boat howitzer system (which exceeded expectations, mind you).  So there is some carry over of that intent.  But the part we want to consider here is within the section discussion ammunition for those boat howitzers:

Within the last fifty years, another projectile, the shrapnel shell, or spherical case shot, has been contrived, partaking somewhat of the nature of the shell and the canister, and in a great measure superseding the plain shell, where troops are fairly open to its action.

Dahlgren continued on, continuing to slight the projectile class with the label of “novelty”, while discussing the evolution of shrapnel – from Napoleonic times up to the 1850s.  But this was not to say Dahlgren did not rate shrapnel of use.  He found shrapnel of value beyond the range of canister.  And he added that specifically applied to naval operations, shrapnel was useful, even within canister’s normal range, to support landing operations.

As to the use of shrapnel:

It is designed to burst the shrapnel in front of the troops exposed to it, and at just such a distance and height as to disperse the charge of balls among them.

Here the difficulty lies.  If the shrapnel burst too high, too near, or too fr, then it is alleged by the objectors that its power is lost, or so far diminished as to be trifling.

The conditions to an execution so exact are said to be: –

  1. In appreciation of the distance.
  2. In timing the explosion.
  3. In adjusting its height above the object.

When bodies are moving with velocities of several hundred feet in an instant, spaces of time which it seems ridiculous to attempt the appreciation of by ordinary means, become not only important, but very plain to the perception, by the differences in the explosion.

Yes, we see the same issues discussed in my earlier post, but yet simply related by way of illustration.  Dahlgren was picking at this problem….

The importance of knowing the distance can hardly be over estimated, and the difficulties of making even a tolerable approximation to the truth are not likely to be undervalued by artillerists.

Emphasis mine.  Given that assessment, Dahlgren approached the problem in his typical manner – starting with an analysis to define just what the problem was.  With respect to the first point, distance, he noted practices that might be employed to train crews to better determine range.  Furthermore, he pointed out the naval gunners had the advantage of seeing water thrown up by the shrapnel, an advantage over shrapnel fired over land.  And he added:

The adjustment of the fuse to the distance, and the altitude of explosion, are regulated to the elevation; and therefore, the three conditions to good effect may be said to depend mainly on a correct knowledge of the distance.

With that established, he saw the need to test….

Considerable experiment will be indispensable to determine accurately the proper regulations of elevation of gun, time of fuze, and height of explosion; and systemic practice must be resorted to afterwards in order to familiarize officers to the use, and enable them to make effective application, of the shrapnel.

Or in other words, put this down in a manual so all can be trained on the practice and the practice be made repeatable.  Yes, the brass ring of all doctrine writers!

But this was not simply an exercise in establishing range tables and providing range estimation training.  Shrapnel behaved differently than shot and shell.  And that was not necessarily a bad thing:

It is in the peculiar dissemination of its balls that the shrapnel promises some corrective for errors in the estimation of distance.  Following the course of the trajectory, with a velocity not less than that of the shrapnel at the instance of explosion, they radiate from the case in the form of a cone; and, when projected on the horizontal plane, take an elliptical figure, the greater axis of which coincides with the continuation of the trajectory, and is much elongated, particularly at the low elevations.

We might call this a “shotgun pattern” of sorts. Dahlgren called it a “jet of balls”, adding the pattern was tighter the closer one is to the point of the burst.  In order to fully understand this behavior, Dahlgren cited some test data:

Three muslin screens were stretched on upright frames over the water, fifty yards apart.  In dimensions, they were twenty feet long and ten feet high.


A frigate’s launch, carrying a 12-pounder of 750 lbs. in the bow, was placed 545 yards from the nearest screen.

Its charges were one pound.  The elevation by sight 1.3 inches.  The motion of the boat precluded the use of an instrument for this purpose.

The shrapnel (charged) averaged 11.4 lbs., containing 80 musket balls (17 to the pound), and four ounces of powder.

The fuzes were two seconds, and such as are issued to the service.

Eight rounds were fired with the following results: –


The gradual increase of the dispersion with the distance is exemplified by the number of balls in each screen, the mean of these eight rounds reducing the effect one-third for 50 yards, and two-thirds for 100 yards.

Dahlgren went on to work on variables which caused variations with the distance of the burst.  And he provided some insight into the behavior of ricochets.  But, while cautioning the test was a small sample size, he did offer a third party observation:

From the data above, the distances of 60 to 150 paces in front of the object (50 to 129 yards), with heights of four to fifteen feet, have given good results with cannon, apart from the ranges.

So here we have a planning figure – shrapnel should explode 50 to 129 yards in front of the target at a height of 4 to 15 feet in order to achieve the best effect, given dispersion of the balls.

As for performance of the balls on the target, Dahlgren observed:

The force of the balls was sufficient, in every instance, to pass through pine boards one inch thick, placed behind the screens, the distance of the third screen from the explosion being sometimes 150 yards.

So we add to the planning figure the effective range of shrapnel – 150 yards beyond the burst.

Dahlgren departed analysis of the test results and moved on to summarize opinions about the merits of shrapnel, which was certainly a spirited debate among military authorities of the time.  At the end he suggested a conclusion (as Dahlgren, being somewhat a “staff officer” at this time, was not the decision maker):

Is it not more judicious to improve its operation to the utmost, by thorough experiment and practice, and to look to the results of actual service for a settlement of the several issues raised; neither blindly confiding in the alleged superiority of the new projectile, nor, on the other hand, allowing its probable merit to be depreciated by a too ready skepticism?

Let us put a healthy highlight on Dahlgren’s suggestion.  On one part, we see tacit admission the behavior of shrapnel was not well documented.  On the other part, he exposes a situation we, removed from things 150 years, may not appreciate – Not all authorities, Army and Navy, were convinced shrapnel was worth the trouble.  That’s important!

However, let’s close this on the technical side.  Dahlgren determined shrapnel was most effective when bursting 50 to 130 yards (I’m rounding) in front of and 4 to 15 feet above the intended target.  That’s the factor we seek to apply to practice… or more accurately for the purposes of discussion, that is the factor we want to see evidence of being applied to instructions given to gunners.  Got it?

(Citations from John A. Dahlgren, A System of Boat Armament in the United States Navy, Philadelphia: A. Hart, 1852, pages 37-50.)



Another Dahlgren recovered from CSS Georgia … and a rifled one at that!

The days since the Sesquicentennial ended have been very interesting for those of us with an interest in heavy Civil War ordnance.  Three cannon came out of the PeeDee River in South Carolina, once armament of the CSS Pee Dee.  Two rare Brooke rifles and a Dahlgren shell gun.  And there is the ongoing recovery operation in the Savannah River, aiming to remove the CSS Georgia’s remains before dredging widens the ship channel there.  Earlier this summer the Army Corps of Engineers shipped four recovered cannon, to include a Dahlgren smootbore and a 6.4-inch Brooke Rifle to Texas A&M University to undergo preservation treatment.

And last month, authorities announced a surprise finding… another Dahlgren gun found in the Savannah River.  That makes a total of three Dahlgrens recovered this year.  And this one is identified as a rifled Dahlgren.

DahlgrenPress releases from the Army Corps of Engineers provide only details as to the weight, being 9,000 pounds. That weight puts the weapon in the IX-inch Dahlgren class. But I am unfamiliar with any rifling of that type, class of weapon by either Federal or Confederate sources.  It is possible, given the general weight provided in the release, that the Dahlgren was cast to the IX-inch form but bored out to a smaller caliber.  Likewise it could have been a smoothbore with groves added.  Confederate sources used both practices to provide rifled ordnance during the war.  Views of the cannon in the photos lead me to believe this is a IX-inch that was rifled. Interesting to note, authorities speculated there would be a second Dahlgren based on documentary evidence.  And the recovery of rifled projectiles of a sort not matching to the already identified weapons lead them to believe this second Dahlgren was there at the river bottom. Here are some more photos of the Dahlgren:




After 150 years and nine months under the Savannah River, the Dahlgren is now on dry land.  I’m looking forward, years ahead, when all the artifacts from the CSS Georgia will be on display.

CSS Pee Dee update: Two Brooke Rifles and a Dahlgren pulled out of the PeeDee River

News broke yesterday of the successful recovery of three Civil War cannon from the PeeDee River, all from the gunboat CSS Pee Dee.  In case you missed it, here’s a few of the reports:

South Strand News

The State (Columbia SC)

South Carolina Now

The Florence County museum offered a post and album of photos on their Facebook page.  The guns are 7-inch and 6.4-inch double banded Brooke rifles along with a IX-inch Dahlgren.  All these weapons are of historical significance and rare in their own right.  But the Dahlgren perhaps a little more so.  And one of the photos shows markings from the Dahlgren:


Registry number 513.  That should, if I’m reading my references correct, be from a lot produced by Fort Pitt Foundry.  But what makes this weapon of real interest is that some sources connect it to the USS Southfield, sunk at Plymouth, North Carolina on April 19, 1864.  The Confederates recovered the Southfield’s armament (which also included a 6.4-inch Parrott rifle which I believe was later used in the Cape Fear defenses).  So you might say this Dahlgren has a bit of a story to tell from both sides of the lines.

The articles tell us these guns already have a home:

After conservation, artifacts will be exhibited at the Florence County Veterans Administration building at the Florence National Cemetery.

A win-win, if you ask me.

Ask for IX-inch guns, you get XI-inch guns: Naval support for the Third Major Bombardment

Last week, I mentioned this gun that was put to use on Morris Island in the summer of 1864:

At the end of July, 1864, Major-General John Foster requested support from Rear-Admiral John Dahlgren to sustain the Third Major Bombardment of Fort Sumter.  In addition to asking for replacements for burst heavy Parrott rifles, Foster asked if the Navy might loan some heavy smoothbore guns.  Foster asked for IX-inch Dahlgrens, but his subordinate, Brigadier-General Alexander Schimmelfennig, felt XI-inch 0r XV-inch Dahglrens would be more suitable for the work.  While Schimmelfennig had a cordial relationship with Dahlgren, I don’t think he pressed the Admiral directly on the issue.  Likely, Dahlgren had more of the XI-inch guns on hand, as the IX-inch guns were heavily used by the smaller blockaders and the XV-inch guns were for the monitors.

On August 5, 1864, Foster wrote to Schimmelfennig to announce the Naval “reinforcements” for the Third Major Bombardment:

Admiral Dahlgren has declared his willingness to lend six 11-inch guns, with carriages, implements, and the requisite officers, crew, and ammunition. The guns are to be landed by the navy at Light-House Inlet, and will be transported to their positions by the army. It is recommended, however, that at high tide the scows used for carrying the shells be run up as high as possible on the beach near the battery and the shells be thrown overboard, so that they can be picked up at low tide by the wagons and taken into the battery. Four 100-pounder Parrott guns will be sent up also as soon as transportation can be had. I will borrow from the navy some 100 and 200 and 300 pounder ammunition, and send it up at the same time, if possible.

Six XI-inch Dahlgrens and four 100-pdr Parrotts to add their weight to the bombardment falling on Fort Sumter. And the Army would receive ammunition to refresh their depleted stocks.  Notice how these would be delivered:  directly over the beach. In fact, dropped on the beach to be retrieved at low tide!  And I do like the use of the verb “borrow,” as if the Army intended to give those shells back.

Foster used the same letter to discuss the ongoing investigation of the failed raid on Fort Johnson.  But after briefly touching upon that matter, he turned to the care of ordnance used in the bombardment.  Referencing the ordnance report from the end of July, he wrote:

I likewise inclose an official copy of the ordnance report from your command, with indorsements thereon, and your attention is invited to indorsement from Lieut. John R. McGinness, chief of ordnance, who states that there is a good supply of lacquer on hand, and that he even used some himself when up there, instructing the men how to lay it on.

The report of the chief of artillery for the Northern District states that the suggestions of R. P. Parrott have not as yet been put into practice. You will cause an investigation to be had in this matter at once, and ascertain with whom the fault of this negligence lies, and have orders issued immediately to lacquer the shells, as per instruction given by Lieutenant McGinness, chief of ordnance, Department of the South, when in your district. The officer who is responsible for this negligence should be punished.

Lieutenant John McGinness complained the interior of the shells were not varnished as recommended by the weapon’s inventor.  And he leveled blame on the artillerists:

As soon as received, Captain Parrott’s letter to the major-general commanding, recommending that the interior of his shells be coated with lacquer or varnish, a copy was made and forwarded through the ordnance office, Morris Island, to the chief of artillery Northern District. An abundance of lacquer has long since been sent to Morris Island and the ordnance officer has been directed to send a supply of it to the batteries. A portion of the 12 shells herein mentioned were varnished by my own hands. I stood over the man until he had completed the balance, and I venture to say that had I not done so even this small number would not have been tried. Why were there not more varnished by the officer commanding the work (Putnam), as plenty of material remained, and give the suggestion a fair trial? I requested the chief of artillery that morning, after I had these shells varnished, to have others prepared in the same way, using lacquer. I respectfully submit that too little interest is manifested by the commandants of batteries in the working, care, and management of their guns, and that this fact more than any other accounts for the great number of guns burst at the front. Too much is expected of ordnance officers.

McGinness felt the artillerists should take an interest to ensuring their ordnance was properly prepared… and not assume the ordnance officers were handling those details.  It’s the little things, such as a light coat of varnish, that spell the difference between a shell sent to a precise point in the rubble that was Fort Sumter and a premature explosion damaging the gun and possibly killing the gunners.

(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 192 and 216-7.)



“Conformable to your request, six 100-pounder Parrotts will be loaned.”: Naval reinforcement for Fort Sumter bombardment

A subtle point made by Lieutenant-Colonel William Ames in his in-progress report on the Third Major Bombardment, on July 27, 1964, was the attrition rate of the heavy Parrott rifles.  These guns – the 6.4-inch (100-pounders), 8-inch (200-pounders), and 10-inch (300-pounders) – not only threw the greatest weight, but were more frequently used in the Third Major Bombardment than their smaller brothers.   The loss of one gun burst and two out of action for repairs put limits on the sustained rate of fire against Fort Sumter.  Another approaching limitation on the firing rate was the supply of ammunition.  Having expended over 6,000 rounds by month’s end, even the large stockpiles on Morris and Folly Island were drained.

If the pace of fire slackened, the Confederates would have more time to repair.  Major-General John Foster could not have that.  He wanted to knock the fort down.  More so, Foster wanted to increase the pace, if possible, by adding more guns to the bombardment.  Reluctant to wait for more shipments from the north, he inquired with Rear-Admiral John Dahlgren on July 30, 1864:

I have the honor to request the loan of six 100-pounder Parrott guns, to be placed in a new battery erected on Cumming’s Point. I also beg leave to say that I will avail myself of your offer of some 9-inch guns for the battery at Spanish Wells, and will send for them in a day or two. I shall be obliged to borrow of you the ammunition for these guns, as we have none.

Dahlgren, in the spirit of good joint operations, responded promptly:

Conformable to your request, six 100-pounder Parrotts will be loaned to you, and are at your disposal when it suits your convenience to send for them. I expected to have obtained the 9-inch guns from the Wabash, but she has left this port, and I have required on the Bureau for some. When they arrive I shall be glad to meet your wishes.

On paper there were “Army” and “Navy” models of these large Parrott rifles.  But the only notable difference between the models were the markings.  All Parrotts larger than 5.2-inch (30-pounder) had blade-type cascabels with breeching blocks.  Sight arrangements varied for mountings on ironclads, pivot batteries, or army siege carriages.  But those were fittings modified locally by artificers.  These were guns which Foster could put into battery without delay.

As for the 9-inch guns requested, eventually the Navy loaned Dahlgrens.  But of a larger caliber, as captured in a wartime photograph:

Unlike the Parrotts, the Dahlgren gun required a wooden carriage, seen here.  Looks rather out of place sitting on a wooden platform in the beach sand.

(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 200-2.)

Shellguns for the spardecks: Dahlgren’s X-inch Shellguns

Back when discussing Rear-Admiral John Dahlgren’s shell guns and their relatives, I used this chart to illustrate the lineage:


The IX-inch shell guns, XI-inch shell guns, and XV-inch turret guns, which saw extensive service, particularly in the waters off Charleston, I’ve given some attention already.  And those guns deserve more attention as time permits.  But today let me look to one of the less common members of the original family of shell guns – the X-inch shell gun.

Prior to Dahlgren’s work, the Navy had in the inventory a limited number of 10-inch shellguns.  These were named 10-inch Shell Gun of 86 hundredweight.  The guns were often cited as Paixhans guns, in reference to the French weapons the Americans used as a model.  West Point Foundry produced thirty-three of these in 1841-2.  Those shell guns were placed in the pivot gun positions  on the spar decks of several pre-war side-wheel steam frigates, namely the USS Mississippi and USS Susquehanna.  But the problem with the gun was it’s limited powder charge and handling weight of the shell.  A four pound charge pushed a 104 pound shell.  The propellant charge was significantly lighter than the British equivalent.  This shell was heavier than contemporary British practice by a factor of almost twenty pounds.  So the American 10-inch “Paixhans” compared unfavorably to similar weapons of the most likely adversary.

When Dahlgren set out to improve the Navy’s ordnance, he put emphasis on placing the largest possible calibers in every position in order to overwhelm any adversary with the sheer weight of fire.  That in mind, Dahlgren wanted to place XI-inch shell guns on the pivots of the new steam sloops being built in the first half of the 1850s.  Even though trials proved the 138-pound XI-inch shells of his design could be handled by gun crews, his superiors were unmoved.  So Dahlgren designed a X-inch gun for those pivot assignments on those new sloops.

Dahlgren’s Memoirs indicate contracts for seven X-inch guns each went to West Point Foundry and Cyrus Alger in December 1854.  West Point produced nineteen in 1855-59.  But records for Alger are a blank.  The only other recorded production run was a batch of 10 from Seyfert, McManus, and Company during the Civil War. Those known production runs are represented on the table below, comparing the particulars of the Dahlgren shell guns:


In service, the X-inch shell guns fired a 103 pound shell, including the filling and sabot.  The table below compares contemporary shells of other calibers:


The service charge authorized for Dahlgren’s X-inch shell guns used a 12.5 pound charge – over three times that of the older shell gun of the same caliber.  The table below is from the 1860 Naval Ordnance Manual:


The heavier charge reflected the improvements made by Dahlgren to gun design, which allowed those heavier pressures in the gun.  During the war, the rating went up to 15 pounds when firing at long range.  The normal charge remained 12.5 pounds, while 10 pounds was recommended for close range (or double shotting).  (See the 1866 version of the service charge table to compare with other guns.)

As for range, the 1866 manual credits the X-inch gun with a 3,000 yard range, at 11° elevation, using the standard 12.5 pound charge.  The larger XI-inch gun could reach only 2,870 yards at the same elevation.  And the IX-inch gun only 2,788 yards at 11°.  So the X-inch gun seemed to have had an advantage in range over the others in the family.  However, the largest gun of the three types had a shell with a six pound bursting charge (and the kinetic energy of 130 pounds of iron).  The X-inch offered only a four pound bursting charge inside 97 pounds of iron.   Perhaps the destructive potential of those larger shells was of greater advantage than range.

The original ships receiving the X-inch guns were the USS Merrimack, USS Wabash, USS Minnesota, USS Roanoke, and USS Colorado.  Two of those ships, of course, were later converted to ironclads – one for each side, mind you.  The two X-inch guns from the Merrimack may have been the “two 10-inch columbiads” reported captured when Virginia seized the Gosport Navy Yard on April 21, 1861. The USS Brooklyn received two X-inch shell guns and USS Pocahontas received a single gun.

Since I’ve been on a Charleston swing of late, let me mention the service of those ships in those waters.  The Brooklyn and the Pocahontas were involved with the early war operations there, but moved to other stations after the first year of the war. The Wabash served in the South Atlantic Blockading Squadron through the summer of 1863 and fired her share of shells at the Confederate forts.

The X-inch Guns conformed to Dahlgren’s design standards to include the cylindrical reinforce and sweeping curves.  The guns were cast solid, with excess metal around the chase to improve overall strength of casting.  The excess was trimmed off and the guns bored out in the traditional manner at the foundry.  Normally, at this point in a “cannon” post, I start the walk around photos.  Can’t do that here.  Of the twenty-nine known produced not a single X-inch Dahlgren is known to survive.  But there is a photo of one serving on the Wabash during the war.

The crew steals the show here.  Particularly that fabulous beard on the right.  The caption indicates this was the aft pivot gun on the Wabash.

The X-inch Dahlgren shell guns also saw service on the Mississippi River gunboats.  But the more widely produced IX-inch and XI-inch guns far outnumbered the X-inch guns in any theater.

Guns of the USS Monitor

Yesterday I had the opportunity to look at the two XI-inch Dahlgrens recovered with the turret from the USS Monitor.  The folks at the US Monitor Center have these in tanks undergoing treatment.  The guns will be there for several more years before this process is complete.  But even in the tanks, these guns reveal an interesting story.  So let me offer a bit of a “walk-around.”

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Or more precisely, a “walk around the tank.”

And before getting too far, let me suggest the walk-around offered for the USS Keokuk gun in Charleston for comparison.  On the books, these are the same type of guns.  But the guns differ in details.

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With the guns under water, being treated for being under water for well over 100 years, its hard to get a photo without a little glare.  But someday these will be out on display.

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The front sight mass on one of the guns has tapped holes for mounting the front sight.  Would be interesting to see if that gun had a front blade sight.

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When cast the sight mass and other fixture attachment points were un-finished – meaning the holes were not drilled.  When placed into service, an artificer would drill the holes and a specialist would “sight” the piece.  If for any reason the sights or lockpieces were removed from the gun, a standard practice was to fill those holes with zinc or another metal.  Otherwise the hole presented another surface area for corrosion to take hold.

The stampings on the breech are clear as the day they the guns were accepted by the inspector.

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Notice here the right side lockpiece block.  It was altered for use. And think about the times fire went down the vent there to ignite powder propelling a shot against some target… such as the CSS Virginia.

Some other markings on the guns are in honor of that historic fight.  Hard, with the glare, to get a st right on view.  But you can make out “Worden”, “Ericsson” and “Merrimack.”

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Yes, to the Federals, she was still the Merrimack.

Other objects in the tanks include one of the carriages.

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Again, fascinating artifact.  I don’t know of any other XI-inch monitor carriages extant today. When the preservation is complete, these will complete many volumes of research.   These also serve as a reminder these were not simply “guns” pulled up out of the sea, but guns in a service state with equipment and accessories.  Some of those are finished with treatment.

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Some of these were still attached to the guns when recovered with the turret.

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And many of these have stampings which provide sharp details to the story of the Monitor.

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A historic record beyond just paper and ink.  Real physical primary sources, if you will.

You can read more on the preservation and conservation efforts on the Monitor‘s turret at the USS Monitor Center Blog.  You can also see some better photos in the latest issue of Civil War Times Illustrated.