August 19, 1864: “Receipt of heavy cannon by this department is insufficient” and the Ordnance Department wants more Rodman Guns

A theme I have researched for many years is wartime cannon production, on the Federal side, and how that reflected defense policy more so than wartime needs.  While the Confederate side of the story is largely “not enough capacity, make what we can,” the Federal side is much more complex.

One might guess, without consultation of the figures, that field guns would be in high demand during the war, with large numbers rolling out of the foundries throughout the war.  But the actual figures for weapons accepted by the Army point to a more complex story.  Field gun production dropped off after the second quarter of 1864, with no further Napoleon 12-pdrs accepted.  On the other end of the scale, production of large caliber weapons for seacoast defense increased greatly throughout the war.  Yet the Federals faced no direct, immediate threat of seaborne attack.  Only distant threats from Confederate raiders and ironclads… or the potential of European involvement.

On August 19, 1864, correspondence from Brigadier-General George Ramsay, Chief of Ordnance, to the Secretary of War, Edwin Stanton, provide some insight into the emphasis on heavy guns.

Sir: As the present receipt of heavy cannon by this department is insufficient for meeting the wants of the country, I desire to present for your consideration certain facts connected therewith, showing the propriety and importance of increasing the supply up to the maximum capacity of our iron foundries. As communicated to you in my letter of the 31st of December, 1863, the number of 8-inch, 10-inch, and 15-inch Rodman guns required for the proper armament of our fortifications on the coast and frontier is estimated, from the best data attainable, at 4,918. The capacity (Army share) of our foundries for this class of guns, in addition to their other work, was stated in the same letter at 612 for the year 1864, at which rate it would take seven years to produce the quantity required.

With no mention of a single Confederate threat, what are we to consider for the definition of “wants of the country”?  Certainly, as seen with requests for Rodman Guns at points like Pensacola, there was a need for such heavy weapons at points under threat of Confederate raiders.  Less threat, however, was present at far flung locations as California where more Rodmans were wanted.  The Army figured a need for nearly 5,000 of these guns to defend “the coast and frontier.”  And we have no mention here of a threat from the Confederates.  Ramsay’s letter is less about beating the guys in gray and more so about national defense policy.

Ramsay pressed to make sure the nation’s coastal defenses were well armed.  And at the rate guns were being accepted, he worried that would take many long years:

The following table exhibits the deficiency in the number of these guns expected to be received in the present year to date, and based on the estimated capacity of the founders engaged in the manufacture:


And why was the Army behind in equipping the forts?

This deficiency is chiefly attributable to the fact that in consequence of the high prices asked by Messrs. Charles Knap & Co., C. Alger & Co., the principal founders, it was not deemed advisable by the War Department in March last to accede to their terms, and such guns as they have delivered in the present year were due on order given prior to January 1, 1864.

Messrs. Seyfert, McManus & Co., of Reading, Pa., accepted a contract for seventy-five 8-inch and 10-inch guns at 10½ cents per pound, which they have nearly filled. We are now paying 13 cents a pound for 8-inch siege mortars and howitzers.

Not only did Ramsay want to spread the work among multiple vendors, he also wanted to engage in what we’d call today “fixed priced contracting” as a measure to block profiteering and benefit to the government:

I inclose a memorandum from the Navy Ordnance Bureau showing the prices now being paid by them for heavy guns. As the magnitude of the work is such as will require years to execute it, and as its accomplishment is of vital importance to the defense of our harbors and sea-ports, I think no time should be lost in expending the money appropriated by Congress for the armament of fortifications, in order to avoid any further rise in the price of material and labor; and I request that I be authorized to make contracts for a definite number of guns to be delivered in specified times, and on the most favorable terms I can negotiate after due investigation, to be approved by you. As the want of a Government establishment of this kind makes us entirely dependent upon private parties, whose capital and experience enables them to exercise a monopoly of this kind of work, I consider the interests of the Government will suffer far more from the interruption in the supply of guns than from any dubious excess in the gains of the manufacturers.

Now there is a bit of a back story involving politics at the Ordnance Department.  I’ll offer the short version, as most readers are no doubt more interested in the guns themselves than bickering among cannon inspectors.  Ramsay was not on good terms with Stanton.  When he took the post of Chief of Ordnance in September 1863, Captain George T. Balch, whom Stanton preferred, was the de facto chief in many respects.  Within a month of this letter to Stanton, Ramsay would request to be relieved from the post.

But the friction between Ramsay and Stanton aside, the fact of the matter is heavy ordnance production increased substantially through the last year of the Civil War.  Those guns were not purchased with a mind to aid in the suppression of a rebellion.  Instead these were procured for “the wants of the country” as defined in engineering surveys of the coastlines.  The Civil War saw Federal military expenditures on a level never seen before in the United States (and at a level not exceed for another half century – during World War I).  And a substantial amount of that expenditure was to ensure the nation’s defenses were brought up to a healthy state… while the Congress was willing to keep writing the checks.

(Citation from OR, Series III, Volume 4, Serial 125, pages 626-7.)


August 10, 1864: Big guns going to… not Charleston… not Petersburg… but San Francisco!

Maybe this sesquicentennial stuff is limited to east of the Rocky Mountains and mostly even east of the Mississippi at that.  Yes, most of the Civil War was fought in what we’d consider today the “eastern” United States, with relatively little activity in the “west” of the modern definition.  But as all good Civil War buffs know, there was indeed activity in the western part of the country… and in particular California played a critical role in the Federal war effort.  There’s that four letter word – G-O-L-D.

Follow that gold, and the path led to San Francisco.


Or more specifically passage through the Golden Gate.  Today we think of this:

But during the Civil War, the Golden Gate looked like this:


And this, looking over Fort Point at the narrows of the Golden Gate:

Fort Point was, at that time, the main defense of the passage.  Rushed to completion early in the Civil War, the work reflected military thinking of the pre-war era.  After three years of war, that Third-System brick fort was considered inadequate.  The fort’s designed armament consisted of older seacoast guns and pre-war Columbiads – and little of that was in place.  She lacked more powerful Rodman guns or large caliber rifles.  The pressing threat was steam powered Confederate raiders, which might make the passage before a few rounds were fired from the fort.  But the most dangerous threat was an ironclad like this one:


Intended to be the CSS Stonewall, the ship had a interesting history beyond the Civil War… but that’s for another day.  Ironclads armed with powerful rifled guns cold stand in the channel and render Fort Point inert, with immunity from all but the largest cannons on shore.  And that threat came from both Confederate and possibly foreign flagged warships.  If the Europeans intervened in the Civil War, San Francisco was more likely a target than New York.

Major-General Irwin McDowell, exiled to the Department of the Pacific (which was probably about as “cushy” a job as one might get in the Civil War, by the way), described the particulars of the Golden Gate passage from a military perspective in a letter to the Engineer Corps, in Washington, on July 27, 1864:

The charts of the harbor will show you the islands, the width of the channel, and depth of the water, but will not inform you of the prevailing winds which blow from the sea right into the gate; nor of the fogs which for a large part of the year enable vessels (as was the case when I arrived) to get quite inside before being seen. The Golden Gate is about as wide as the Narrows at New York, but the gate here opens right at once upon the broad ocean and not into a lower bay. On account of the width of the channel at the Golden Gate and the deep water at Lime Point, the work at Fort Point, about the size and kind of Fort Richmond, would be no barrier against steam vessels. Lime Point is a cliff with water at its base so deep and so swift that a lead has never (Captain Elliot, engineer, says) found bottom.

The point, which McDowell amply described, was that steamships could make a relatively fast passage, through deep waters and gain San Francisco.  And if timed right, fog and other factors would work against the defenders.

All of this was known by authorities in Washington.  In 1856 a survey of the terrain brought back numerous recommendations to fortify the bay. Those included additional batteries to supplement Fort Point and located on Alcatraz, Yerba Beuna, and Angel Islands, Point San Jose, and, most important to the Golden Gate, Lime Point opposite Fort Point.  I’ve highlighted some of those on a snip from the 1859 coastal survey map (which, by the way, indicates that someone had “cast a lead” into those waters to figure out the depth):


By 1863, none of these options advanced far, as the Department of the Pacific lacked resources – chiefly heavy guns.  In August 1863, a board of officers suggested focused effort – and funding – for batteries on Lime Point, Point San Jose, and Angel Island, with the caveat that Lime Point would be a costly endeavor.  A year later, McDowell made the same comment about Lime Point:

To blast this cliff and build up a castle-work of masonry on the shelf is the labor of years at a cost of a million. It would not meet the existing emergency to do anything with it, and I would not in the present exhausted condition of the country advise its being even commenced.

However, McDowell offered another option:

 Within a few hundred yards seaward of Lime Point, between it and the light-house, is a little valley–a recess in the line of cliffs–where a water battery could be constructed in a few days, and which, if suitably armed and the overhanging heights properly occupied, would do all that could be done to give immediate strength to the first line of works. This valley is a couple of hundred yards farther off from Fort Point than is Lime Point, and should have heavy guns, some of them rifled.

McDowell went on to suggest other points, further into the harbor, where batteries were needed.  Somewhat like Beauregard at Charleston, McDowell wanted to build a ring of batteries to prevent any safe anchorage within the bay. But McDowell had much more, and deeper, water to cover.

Regardless of the placement of these batteries, McDowell needed guns.  On August 10, 1864, Chief Engineer Brigadier-General Richard Delafield responded to McDowell in regard to the defenses of San Francisco:

The effect of building and arming these batteries would be to bring a certain portion of the bay under fire which is not now under fire. But the vessels could find many other places to anchor, and still be out of reach of any batteries we might establish. A board of engineers has within a year considered the subject of additional defenses at San Francisco, and has come to the conclusion that it is best to bring a certain belt, or part of the harbor, through which all vessels entering it from sea must pass, under as heavy fire as practicable at the earliest day, in the first place, and after this is effected the subject of covering other portions of the bay with fire is to be undertaken in connection with floating defenses. This appears to me to be a prudent policy, and the most that we can undertake while our supply of ordnance suitable for these purposes is so very limited.

In short, he preferred to arm the Golden Gate.  Delafield went on to suggest imposing an administrative solution in the near term – forcing all foreign vessels to anchor at points under the existing defenses prior to entering the bay.

But help was on the way:

A due proportion of such ordnance as we have been able to obtain has heretofore been allotted to San Francisco, and, upon notice just received from the Ordnance Department that there are now some guns available for distribution, I shall ask to have sent to San Francisco the following: Three 15-inch guns, ten 100-pounder rifles, two 200-pounder rifles.

So in the middle of 1864, with commanders in active theaters such as Mobile Bay, Charleston, Petersburg, and Atlanta calling for heavy ordnance for use in siege operations, the Ordnance Department was to allocate fifteen of their largest and finest weapons to defend San Francisco.  And more such heavy guns would follow.  By the end of the Civil War, San Francisco would boast some of the heaviest coastal defenses in the Pacific.  Justifiably, after all.  It was the GOLDen Gate.

UPDATE:  I should point out, this image from 1908 demonstrates both the fears expressed in 1864 while at the same time the ultimate resolution of the military defense of San Francisco:

You must click and zoom in to get the full effect.  That’s the US Atlantic Fleet making a call at San Francisco in May 1908. No getting around it, the US needed a two ocean navy.

(Citations from OR, Series I, Volume 50, Part II, Serial 106, pages 921-2, 936-7; Base maps used above are “From San Francisco Bay to the northern boundary of California,” 1855 and “Entrance to San Francisco Bay, California” Coastal Survey of 1859; “Stonewall-Kotetsu“. Licensed under Public domain via Wikimedia Commons.; other images from WikiCommons or Library of Congress collection, where linked. )

15-inch Guns for Pensacola Harbor

Military activities at Pensacola, Florida had long faded even from the back pages of the newspapers by 1864.  At the onset of the secession crisis, Fort Pickens had been, like Fort Sumter, one of the “hot spots” that lead to war.  But with the Confederate withdrawal in early 1862, that Gulf Coast harbor was in Federal hands.

But that did not not mean the city was safe and secure.  On May 9, 1864, Rear-Admiral David G. Farragut, commanding the West Gulf Blockading Squadron, sent an inquiry to the Navy Department discussing a means to nullify a threat he perceived to Pensacola:

I would most respectfully suggest that an application be made to the War Department to have two 15-inch guns placed on the Old Spanish Battery at Barrancas and two in an earth-work on the beach, on the western front of Fort Pickens, as I think they would be sufficient to render this port safe against the entrance of almost any enemy.

So what “enemy” was Farragut considering?  Earlier in the year, Farragut expressed concerns of a breakout by Confederate ironclads reported in Mobile Bay to the west.  From there, he feared, the ironclads might operate against Pensacola, New Orleans, or other points to disrupt the Federal blockade.

Farragut’s request processed through the Navy Department and then over to the War Department in somewhat good speed, on May 31.  In the War Department, the request went first to the Chief Engineer, Brigadier-General Richard Delafield, who referred to the Chief of Ordnance, Brigadier-General George Ramsay.  Ramsey, responded affirmatively on June 14:

I approve of the recommendation of Admiral Farragut, believing that guns of heavier caliber than are now mounted are wanted for the fortifications of Pensacola Harbor.  The four 15-inch guns will be supplied by this Department, and with implements, carriages, and ammunition, whenever the arrangements for mounting them are completed and a requisition for them is made to this office.

“Sure!  That’s a fine idea!  But we have to wait until the proper forms are completed.” And that’s where this thread unravels. The only 15-inch guns at the War Department’s disposal were Rodman guns.  Though features in the Washington Defenses, most of those caliber weapons went to seacoast defenses protecting the northern ports (New York in particular).  A few went west to California, and is the subject of a sesquicentennial “novelty post” I have in the queue.  Despite what some secondary accounts might say, no Rodmans were used at Fort Pulaski or on Morris Island.  So were four 15-inch Rodmans sent to Pensacola during the war?  If so, for good measure, that would be a rare employment of the weapon south of the Potomac.

I know Rodman guns were present in the Pensacola defenses post-war.  But like similar seacoast defenses at Charleston, the large Rodmans arrived after the war was over and served through those lean years until disappearing, breechloading guns arrived to be mounted in concrete batteries.

For those who don’t worry about the difference between an Ordnance Rifle and a Rodman Gun, this is probably a “so what?”  But if the War Department was willing to part with four 15-inch Rodmans to protect Pensacola, that does speak to the value placed on that port and to the evaluation of the threat.

(Citations from OR, Series I, Volume 35, Part II, Serial 66, pages 108-9.)

Battle of the Ironclads: “What if” Rodman’s guns were used?

Today being the 150th anniversary of the clash between the USS Monitor and CSS Virginia, posts and articles about the battle are all over the internet.

The Civil War Navy Sesquicentennial is in full “ironclad” mode with several posts relating to the battle, including the “big buzz” about the facial reconstruction from the remains recovered from the USS MonitorAndy Hall has a good piece on the reconstructed faces, with some comparison to wartime photos, the on the Civil War Monitor (Magazine) blog page.  But look for more posts about the ironclads today and through the weekend.  With the Civil War Navy Conference running through this weekend (I’m preparing to head out as I type this), no doubt we’ll have more to post over the next few days.

The Civil War Trust has an excellent “battle page” devoted to Hampton Roads.  The maps linked on the page detail the tactical actions that took place on both March 8 and 9, 1862.  Another map provided on the battle page, of a location in the news of late, shows the details of Fort Monroe.   That brings me to a “What if?” question for today.  What if this gun was in place on March 8-9, 1862?

That is, of course, the 15-inch Rodman prototype gun which I wrote of extensively in January.  The “Lincoln Gun” along with the “Union Gun,” a 12-inch rifle prototype, were at Fort Monroe in March 1862.  But neither played into the fight.  Although the 12-inch rifle sat on a barbette carriage the time of the battle, the 15-inch remained unmounted until later that month.

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15-inch Rodman Prototype at Fort Monroe today

Speaking technically, these guns did have the capability to fire upon the CSS Virginia and the other Confederate vessels (don’t forget there were several gunboats involved) as they sortied on March 8.  The 15-inch gun’s trials indicated a 5700 yard range at 28° elevation, or just over three miles.  Although untested for range the 12-inch rifle no doubt could match that.  Indeed, both guns covered the contested waterways a month later, firing on Sewell’s Point.  So, yes these guns had the potential to engage the Confederate ships.

From a standpoint of logistics, I’m not sure there were ample supplies on hand for the guns.  However, I do find it hard to believe that in March 1862 there were no 15-inch smoothbore or 12-inch rifle projectiles at Fort Monroe.  Perhaps limited quantities at least.  After all, the guns were there for trials.  And trials mean someone is planning to shoot some targets!

Tactically speaking… well, I would raise more than a few objections.  The Army’s gun handling drills assumed target ships would remain slow moving targets attempting to bombard the shore batteries.  The rate of fire for the heavy Rodmans was measured in minutes.  There were no standards for predicting fire against fast moving targets – particularly “dueling” ships locked in their “dance.” Lastly, there were plenty of “friendly” vessels at Hampton Roads which the gunners had to fire around.

But a weapons true effectiveness is not just a simple measure of fire rates and range.  Consider also the impression on the receiving end.  The simple fact that the Rodmans “had the range” might have changed the course chosen by Captain Franklin Buchanan, if not dissuading the sortie completely.  Even with the Rodman guns out of the equation, Fort Monroe boasted several large-caliber smoothbore guns and a few rifles.  Had the CSS Virginia ventured too close, I suspect the Buchanan would have learned a lesson similar to those of Captain Foote at Fort Donelson and Admiral DuPont outside Charleston.  Ironclading didn’t equate to invulnerability.

I would submit that even if the Rodman guns at Fort Monroe had been put to good use in the Battle of Hampton Roads, their effect wouldn’t have changed the inevitable – the steam-powered, armored warship had arrived on the scene.  Naval warfare, and by extension seacoast defense, changed that day.  The Army might “consider” the heavy smoothbore guns effective (even into the 1880s!) but the technological race to the dreadnought was on.

Still I have to ask why the Army didn’t at least “make a show” with the Rodmans at Hampton Roads.

Converted Rodman Rifles: Defending the coast in the time of lean budgets

Earlier this week, Keith Harris asked for a quick cannon identification via Twitter. Feel free to click over to Keith’s picture, but the gun below from Fort McHenry, Maryland is similar.

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8-inch Rifle Converted from a 10-inch Rodman at Fort McHenry

The exterior shape of this gun should look familiar. It’s a 10-inch Rodman. But a close look at the bore reveals something decidedly non-standard for that type of gun. This was a post-war modification to the gun. The story is interesting not only because it involves a Civil War cannon, but also because it carries forward all the way to the 20th century.

During and shortly after the Civil War the Army felt the Rodmans were sufficient to defend the coastlines. The combatants in the war deployed the most advanced warships of the day, and the Rodman guns rated well enough to deal with that threat. However within a decade, developments in Europe eclipsed the Civil War era weapons. Ship builders turned to steel, over the wood and wrought iron of the Civil War. So the coastline defenses needed improved guns.

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Pair of Converted 8-inch Rifles at Fort McHenry

Trouble was the U.S. had a lot of coastline to defend, but not a whole lot of money to spend on guns. Given the limited budget for updates, the Army looked around for options… and saw hundreds of Rodman smoothbores.

Recall that during the Civil War many of the old 32-pdr and 42-pdr guns got a new lease on life as “rifled guns.” With that experience in mind, soon ordnance officers and weapon developers stepped forward with different schemes to rifle those Rodmans. I’ve seen well over a dozen different plans for rifling Rodman guns, including plans for 15-inch conversions to 12-inch rifles. Some even provided for breech loading conversion.

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Muzzle showing breech insertion

The most successful (and I use that qualifier in relative terms) conversions involved the 10-inch Rodman guns. At least four different groups of Rodmans in that caliber underwent conversion to 8-inch rifles. Those four conversion plans required the original gun to be reamed out to fit new bore sleeve, and often a liner, by way of insertion. The sleeve and liner were usually steel, but some early experiments used wrought iron. The groups differed in the technique used for inserting the sleeve (through the muzzle or through the breech) and the number of rifle grooves.

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8-inch Converted Rifle on blocks at Fort McHenry

All told the Army contracted for conversion of over 200 of the 10-inch Rodmans from about 1876 to 1890. After successful tests at Sandy Point, New York, the guns went to the forts as the primary anti-ship weapon in the arsenal. However even at that time, everyone recognized the conversions were obsolete given the armament of European navies. But that was all the Army could acquire given the limited peacetime budgets.

These weapons remained in the Army’s inventory to the end of the century. The 1891 Manual of Heavy Artillery Service provided a range table and a dozen pages of drill instructions.

So 4700 yards range for a 35 pound powder charge. Still not all that impressive compared to contemporary breech-loading, steel rifles. For instance the “new” M1888 8-inch breechloading gun on a disappearing carriage rated over 10,000 yards. But of course the Army didn’t receive many of those “new” guns until the late 1890s.

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8-inch Rifle showing breech insertion plug

These converted rifles remained in the forts even during the Spanish-American War. And a good number of them survive today (as seen in the photos supporting this post). The service history of these guns spans four decades. Heck, these guns rival the B-52 bomber in terms of service life!

The gun Keith photographed is located in the Grand Army of the Republic plot of the Rosedale Cemetery in Los Angeles. I’m sure Keith will have a story to tell about that aspect of the gun’s history on his blog. To me, it looks like a gun which needs some tender loving care… and a few coats of paint.

The Big Rodmans: 20-inch Rodmans, Part 2

In yesterday’s post on the 20-inch Rodman Gun, I’d mentioned the gun pictured below arrived at Fort Hamilton, New York for testing in the fall of 1864.

20-inch Rodman #1

Compared to the trials of the 15-inch gun, the 20-inch gun received a bit more fanfare – and full coverage in Harper’s Weekly. When first fired on October 26, 1864, those in attendance included the gun’s inventor Major Thomas J. Rodman; Army Chief of Ordnance, Brigadier General Alexander B. Dyer; Captain Henry Augustus Wise, Chief of the Navy’s Bureau of Ordnance; and General W. F. Smith. If illustrations accompanying the Harper’s article are any indication, a rather large crowd of onlookers joined the dignitaries.

“Large” was the word for every aspect of the gun. The gun rested upon a specially built 18 ton carriage from the Watertown Arsenal, which was also designed by Rodman. As a measure of the size of the gun, prior to firing, a man lowered himself into the bore of the gun and wormed down to the vent in order to clear an obstruction. 1

The objective of the test was only to verify the gun could fire the heavy projectiles. Unfortunately I’ve never come across any first hand account or report of the gun’s trials. Most secondary sources point to a caption in Francis Miller’s Photographic History of the Civil War. Although Miller incorrectly identified the photo of the 15-inch prototype as the 20-inch gun, he stated the big gun fired four shots in 1864. Firing a 1,080 pound solid shot, the gun used charges increasing through 50, 75, 100, and finally 125 pounds of powder. According to Miller, tests resumed in March 1867 with four more shots. This time charges of 125, 150, 175, and then 200 pounds, fired at a 25° elevation, propelled shot to a maximum range of 8,000 yards.2

Certainly impressive figures, but with the war winding down that massive iron gun was too much for peacetime budgets. Fort Pitt delivered one more 20-inch gun in 1869. This gun also survives today, on display at Fort Hancock, New Jersey. (And again let me thank Bill Coughlin for the photo.)

20-inch Rodman #2 at Fort Hancock

This gun bears the registry number 2 along with its weight marks of 115,100 pounds. John Alexander Kress inspected this monster gun. Once accepted, #2 went to Fort Monroe. In 1876 the gun went to Philadelphia for the Centennial Exposition.3

20-inch Rodman at Centennial Exposition

From there the gun eventually ended up at Fort Hancock among other heavy guns also undergoing trials in the later decades of the 19th century. Thankfully it was preserved to “guard” the post instead of being discarded.

Although the Army received only two 20-inch Rodmans, the guns significantly influenced post-war planning. Plans considered these largest of guns for the critical locations along the seacoast. Over the years, schemes for the 20-inch guns included more advanced carriages, muzzle loading rifled variants, and even breechloading conversions. None of these progressed far. Army acquisition at the time focused on refinement of weapons which could be mass produced in the event of war (since everyone felt there’d be ample warning before any future war). As such, the 1864 testimony of William Wade, part owner of the Fort Pitt Foundry, is worth note. When asked by the Joint Committee on the Conduct of the War, Wade indicated his foundry’s capacity was, “two 10-inch or 8-inch guns per day, three 15-inch guns per week, and two 20-inch guns per month.4

Perhaps we could end the story there, simply saying the two 20-inch Rodmans were great guns that were never called to action. But that’s not the case. In the late 1870’s Peru came shopping for weapons due to heated tensions with Bolivia and Chile. In addition to some of the 15-inch Rodmans, the Peruvians acquired at least on 20-inch Rodman (sometimes noted as a 1000-pdr gun), presumably a surplus weapon at the foundry. During the War of the Pacific, this Rodman, paired with a 20-inch Dahlgren gun also cast by Fort Pitt, was used in defense of the port of Callao. 5 The guns presumably wound up in the hands of the Chileans at that point. Perhaps the big Rodman guns did fire more than a few “test shots” after all.

The legacy of the 20-inch Rodman was to American seacoast defenses in the last decades of the 19th century. While the days of muzzleloading, black powder, smoothbores waned after the Civil War, the range of the 20-inch guns influenced plans. With these larger guns, defenders could control larger expanses of waterways. Instead of just defending the harbor entrances, the Coast Artillery could think about covering likely approaches to the coast. The real change would wait until modern breechloading, rifled, steel guns arrived.


  1. Harper’s Weekly, Volume VIII, No. 412, November 19, 1864, page 749.
  2. Miller, Francis Trevelyan, The Photographic History of the Civil War: Volume 5 – Forts and Artillery (New York: Review of Reviews, 1911), page 137.
  3. Ingram, J.S., The Centennial Exposition Described and Illustrated (Philadelphia: Hubbard Brothers, 1876), page 146.
  4. Testimony of William Wade, “Heavy Ordnance,” Report of the Joint Committee on the Conduct of the War at the Second Session, Thirty-Eighth Congress (Washington: Government Printing Office, 1865), page 86.
  5. Markham, Sir Clements R., The War Between Peru and Chile, 1879-1882 (London: Sampson Low, Marston, and Company, 1882) page 186.

The Big Brother of the Rodman Family: 20-inch Rodman, Part 1

Time to look at the biggest gun made during the Civil War and the largest of the Rodman family – the 20-inch Rodman Gun.

Fresh off the 15-inch Rodman prototype’s tests, and while the nation was rushing to war, Thomas J. Rodman first proposed a 20-inch gun on April 17, 1861:

The entire success which has attended the manufacture and trial of the 15-inch gun, leaves no doubt of our ability to make reliable guns of even greater diameter of bore than 20 inches, and to maneuver and load with facility, and without the use of machinery, guns of that caliber.

A 20-inch gun, one caliber thick, 210 inch length of bore, and 20 feet total length, would weigh about 100000 lbs.

A solid sphere of iron, 20 inches diameter, would weigh about 1000 lbs…. The ordinary service shell need not e over 3.5 inches thick; would weigh about 725 lbs., and contain about 38 lbs. of powder making the total weight of the loaded shell about 763 lbs…..1

Rodman went on to suggest a 100 pound powder charge for these projectiles.  He estimated the force of the solid shot would equal the combined force of six 10-inch solid shot.  Likewise one 20-inch shell would equal the destructive power of seven 10-inch shells.  From those estimates, Rodman drove the point home –

And the destructive effect of such shells, as compared with 10-inch shot, upon iron-clad ships and floating batteries, would be in a much higher ratio; their whole crushing force being brought to bear upon a single point at the same time….

I would point out that Rodman’s concern about defeating ironclads was likely with an eye cast across the Atlantic.

The Army didn’t act upon Rodman’s proposal for two years.  In April 1863 Fort Pitt Foundry received an order for a 20-inch Rodman.2

In the May 1864 American Journal of Science and Arts, a corespondent offered a wealth of details concerning the gun’s casting. As I’ve already described the Rodman method at length, let me highlight one detail not mentioned in Rodman’s earlier experiments. Describing the core inserted into the mold when casting –

The core barrel is a hollow cylinder of iron 17 inches in diameter, closed at one end, open at the other.  It is about one inch thick and is grooved longitudinally or fluted, like a column in architecture, its entire length, the furrows being  1/2 an inch apart.  Around this is wound a rope of the size of ordinary bed cord, and over this a layer of clay 3/4 inch thick is evenly spread and the whole dried.  The object of the grooving is to allow the free escape of gas.  The rope prevents the clay from filling up these grooves.3

Casting took place on February 11, 1864 using three furnaces, and a couple backups.  In about 20 minutes some 85 tons of iron poured into the mold.  After two hours of the prescribed water cooling, foundrymen added more molten metal in order to better form the “sinking head” of the gun.  After about fourteen hours of cooling, the men removed the core. But unlike the smaller Rodman’s this gun was too hot for direct water cooling.  Instead the gunmakers used a continuous blast of air.  Not until February 23 was the gun finally pulled out of the casting flask.  Yet the gun remained warm, and required two more days of cooling.  After that the gun went to a lathe to machine off the excess metal and smooth the exterior.

As seen on the chart below the 20-inch gun dwarfed the other Rodmans in all respects.

Stephen C. Lyford inspected the gun in August 1864, giving it registry number 1.  The gun then went to New York for trials.  And it’s still there today:

20-inch Rodman #1

(Special thanks to my friend Bill Coughlin who provided the photo and posted the nearby marker to HMDB)

I’ll turn to the trials, and then discuss the other 20-inch Rodmans produced by Fort Pitt after the Civil War.


  1. Rodman’s proposal appears in Reports of Experiments on the Properties of Metals for Cannon, and the Qualities of Cannon Powder; with an Account of the Fabrication and Trial of a 15-inch Gun (Boston: Charles H. Crosby, 1861), pages 307-308.
  2. 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 C169, page 265.
  3. Account of the casting of a gigantic (Rodman) Gun at Fort Pitt Foundry, The American Journal of Science and Arts, May 1864, pages 296-301.