70-pdr Whitworth Rifles

Practically every gun on display at the Washington Navy Yard in Washington, D.C. has a story to tell.  And in some cases a couple.  Such is the case for a 70-pdr Whitworth rifled cannon on display just outside the Naval Museum.   Contemporary sources label this gun based on the old weight of shot calculations, but modern historians opt for the land diameter of the rifling, or 5-inch.  I’ll cite the former, as it seems proper from the sources.

70-pdr or 5-in Whitworth Rifle

The history of this four-and-a-quarter ton steel weapon begins in Manchester, England with the Whitworth Ordnance Company.  Yes, you read correctly, steel.  Sir Joseph Whitworth was among the first gun-makers to benefit from the Bessemer process.   As seen in the photo, the gun construction consisted of several reinforcing bands or hoops over a central tube.   The construction of this piece should have matched the diagram provided by J. Emerson Tennent his 1864 book “The Story of the Guns.”

70-pdr Whitworth Plan
70-pdr Whitworth Plan

Overall the gun measured 133 inches.  The base layer of hoops extended 90 inches, with a second 63 inches long mounting the trunnions.  A 37-inch long breech reinforce ended just behind the trunnions.   As noted on the diagram, the gun-maker applied the interior hoop layers with hydraulic pressure.  The outer breech reinforce was threaded into place.  If Whitworth used the same method employed on his smaller weapons, the bands were forced onto the gun tube, with a very slight taper toward the rear of the gun.   Such will factor in later in the “story.”

Muzzle of 70-pdr Whitworth

Whitworth also used a distinctive hexagonal rifling system, as seen in the photo above.  If you consider the rifled grooves of a cannon as load-bearing, hexagonal rifling offers a wide surface area to impart the spin to the projectile.  Whitworth also found the shape easier to machine, and maintain.  (see Tennant, pp 43-46)   Suffice to say I’m being overly simplistic noting the details of the rifling, saving the discussion for another day.  However, for practical purposes, this rifling system required the gun to use special Whitworth projectiles.

Whitworth Projectile
Whitworth Projectile

The 70-pdr promised a range of 5,000 yards firing a solid bolt.  I would imagine that Confederate agents in England, desperate for modern ordnance, were quick to disregard any special munitions requirements for the Whitworths.  Aside from the more familiar (due to its display at Gettysburg) Whitworth field guns, agents ordered at least four of the “70-pdr Whitworth Rifles.”  My speculation is, due to the breeching loop seen on the example at the Navy Yard, is the Confederates intended these rifles for naval applications.  As reinforcement, I would point out the four rifles known to be purchased at that time were shipped on the steamer Princess Royal along with two engines destined for ironclads under construction.

That sets up the first story about these guns.  Four days out from Bermuda, the Princess Royal arrived off Charleston on the morning of January 29, 1863 and attempted to slip through the blockade.  At around 3:15 a.m., lookouts on the U.S.S. Undilla spotted a light heading toward the harbor.  Commander of the Undilla, Lieutenant-Commander S.P. Quackenbush, brought the ship to quarters and slipped anchor.  Aided by rockets fired from the nearby USS G.W. Blunt, the Undilla maneuvered to intercept the Princess Royal, and fired two shots.  The blockade runner altered course and headed to ground on the beach.   With her crew abandoning ship, Quackenbush sent a detachment to take possession of the Princess Royal.  By dawn, the navy inventoried “rifled guns, arms, ammunition, steam engines for ironclads building in Charleston, and an assorted cargo.” (ONR, Series I, Volume 13, page 554)

Inscription on the Breech

As a testament to the capture, the piece on display at the Navy Yard bears the inscription on the breech: “Whitworth 80-pdr [sic] Rifle // captured with 3 others // blockade runner // Princess Royal”.

The Navy later outfitted the Princess Royal as a steam gunboat, serving off Texas and Louisiana.  One of the steam engines carried as cargo powered the USS Kansas, a North Atlantic blockader.  But at least two of the Whitworths remained in the Charleston area.  On July 22, 1863, Rear-Admiral John Dahlgren ordered Commander Foxhall Parker to organize a detachment to man a “naval battery” ashore.  Consisting of two 8-in Parrotts and two Whitworth rifles and located on Morris Island, the battery was to aid the Army in the bombardment of Fort Sumter. (ONR, Series I, Volume 14, p. 385)  And we know the Whitworths were 70-pdrs because of a wartime photograph of the battery.

The Naval Battery at Morris Island
The Naval Battery at Morris Island

And I must say for the record, a more unkempt battery you will not find!  Boots drying on one gun, rammers laying about, and ropes haphazardly draped over the carriages.  Makes me wonder if the sailors’ morale was affected by the service ashore.  Perhaps.

On August 23, Commander Parker offered a rather detailed report of the battery’s activities:

The whole number of Parrott shells expended amounts to 703, of which 373 struck the fort, 252 fell short of went over it, and 78 tumbled.

From the Whitworth guns 222 solid projectiles were fired, of which 98 hit and 124 missed the fort.

Upon the 19th instant one of the Whitworths was entirely disabled by the reinforce bands starting forward, and upon the 21st I discontinued firing from the other, as the shot were continually jamming in the bore, in ramming home one of which four men were killed by a premature explosion of the charge. (ONR, Series I, Volume 14, p. 472)

I could see where the crews might be a little demoralized.

Brigadier General John W. Turner, Chief of Artillery for General Quincy Gilmore’s Department of the South, left no doubt his opinion of the Whitworth in his report, dated November 30, on the bombardment of Fort Sumter.  Turner mentioned premature explosions, wedged projectiles, and inaccurate fire.  He then details the slippage of the bands when:

…subsequently one of them became disabled by the the gun apparently sliding through the re-enforce to the rear.  A displacement of nearly an inch took place, closing the vent completely.  (OR, Series I, Volume 28, Part I, Serial 46, p. 223)

I agree with the conclusions of other historians.   The slippage noted was due to a design flaw – the hoops were not welded nor was the taper sufficient to arrest movement of the gun’s composite layers.

The vent of the survivor at the Navy Yard appears, today, open and unaffected by such slipping.

Vent of the 70-pdr

However, a base ring supporting a sight bracket, apparent in both the plan from Tennant’s book and in the wartime photograph, is missing from the Navy Yard’s trophy.  In the plan, the ring appears separate from the other components of the gun.  Maybe that the ring broke free due to handling.   Or perhaps the slippage due to firing.  Another surviving piece is on display at West Point’s trophy park, and does show signs of the slippage.

So the old 70-pdr Whitworth at the Navy Yard offers a history which blends aspects of technical innovation, a touch of daring with the blockade runner, and perhaps a bit of tragedy with its dangerous, ineffective service.  Today it stands as a trophy of war, honoring those who maintained the blockade during the Civil War.


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

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.

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