RML 9-inch Armstrong Gun
| Company type | Private company |
|---|---|
| Industry | Arms manufacturing |
| Founded | 1859-01-01 |
| Founder | William Armstrong, 1st Baron Armstrong |
| Headquarters | Newcastle , United Kingdom |
| Products | Artillery pieces including RML 9-inch Armstrong Gun |
The RML 9-inch Armstrong Gun was a rifled muzzle-loading artillery piece extensively operated by the naval forces of the Netherlands, Spain, and other countries. It should be distinguished from the RML 9-inch 12-ton gun, which was employed by the British Royal Navy.
Rifled Breechloading Artillery
The United Kingdom maintained a preference for smoothbore cannons for an extended period. In 1850, trials were conducted on existing foreign rifled breechloading guns developed by Martin von Wahrendorff and Giovanni Cavalli. The results led the British government to conclude that these weapons offered limited practical benefits aboard naval vessels. Consequently, Britain predominantly relied on grenade guns alongside 68 and 32-pounder smoothbore artillery. When France began rifling and reinforcing its older cannons, Britain attempted a similar upgrade on approximately 300 of its existing guns; however, these modifications failed during initial testing.
Development of the Armstrong Gun
At the same time, William Armstrong, 1st Baron Armstrong, an inventor and proprietor of a major engineering firm, created a different rifled breechloading gun (RBL), known as the Armstrong gun. In January 1859, his 18-pounder variant underwent highly successful trials. Subsequently, Armstrong was appointed as engineer of rifled ordnance, a newly established position with a substantial salary. Production of Armstrong guns took place both at the Royal Works in Woolwich and at the newly established Elswick Ordnance Company in Newcastle, founded on January 1, 1859, with government backing to separate Armstrong’s official duties from his private manufacturing interests.
For naval use, Armstrong produced breechloaders in calibers of 40-pounder, 70-pounder, and 110-pounder. After some refinements, guns up to and including the 40-pounder (4.75 inch) caliber demonstrated strong performance in both combat and testing scenarios. During the 1863 Bombardment of Kagoshima, eight 110-pounder (7 inch) Armstrong guns performed effectively despite some susceptibility to malfunctions; however, issues with the wedge breech mechanism were satisfactorily resolved.
In 1864, a comparative evaluation involving three types of 70-pounder artillery was conducted. In this assessment, the Armstrong breechloader was outperformed by newer Rifled Muzzle Loaders (RML) designed by Armstrong himself in collaboration with Whitworth. The rifling technique used in the breechloaders was considered inferior and more costly compared to that employed in the newer muzzle-loading designs. A critical limitation was that the breechloading mechanism could not endure the explosive pressures necessary to propel heavy shells at velocities sufficient for penetrating armor. Consequently, Armstrong withdrew his breechloading design from armor penetration competitions.
The Woolwich gun
The Royal Navy reverted to using muzzle-loading rifled artillery, which became known as Woolwich guns. Although Armstrong had enhanced the Royal Artillery facilities at Woolwich for producing his breechloaders, he stepped down in 1863. Subsequently, the Woolwich Works began manufacturing RML guns. These weapons employed Armstrong's technique for barrel construction, and the initial RML designs also incorporated his shunt rifling principle. This association often led to these guns being loosely labeled as Armstrong guns; however, they were not produced by Armstrong's enterprise—later called Elswick Ordnance Company—an Armstrong subsidiary. In 1865, Woolwich introduced RML guns in 7, 8, and 9-inch calibers. These utilized a novel rifling approach known as the Woolwich system, hence the designation Woolwich guns.
The Armstrong RML
While the Royal Navy manufactured its artillery at Woolwich, Armstrong's Elswick Ordnance Company in Newcastle was reintegrated into the Armstrong firm. Elswick continued to produce heavy artillery exclusively for export markets. Among these was a 9-inch RML gun, which the Dutch and other nations referred to as a 23 cm Armstrong gun. Consequently, when foreign navies mentioned an Armstrong gun, they implied it was produced by Armstrong at Elswick. In Britain, however, the term 'Armstrong gun' denoted a specific gun type rather than the manufacturer, necessitating the addition of 'Muzzle Loading' when referring to this particular weapon.
Characteristics
The 23 cm Armstrong RML shared similar dimensions such as length and caliber with the 9-inch Woolwich gun.
Number of coils
A notable distinction between Armstrong and Woolwich guns lies in their coil count. Armstrong’s manufacturing process involved fabricating a steel barrel reinforced by wrought iron coils to withstand internal explosive pressure. Naturally, the section closest to the explosion required greater reinforcement than the muzzle end.
Armstrong’s design retained a higher number of smaller coils, which increased production costs. Visually, these coils appear as protruding humps tapering toward the muzzle, as seen on the 23 cm Armstrong RML mounted on HNLMS Ever. By contrast, the four main variants (marks) of the 9-inch Woolwich gun exhibit fewer coils; Mark I features one less coil than the Armstrong model, and subsequent marks progressively reduced coil quantity and hump prominence as their designs simplified.
Models
Within the Dutch Navy, early examples of these guns differed from later versions. The initial four featured steel barrels that were open at the rear and sealed with a separate steel closing piece backed by copper sheet, secured by a large screw breech. All subsequent Dutch models employed barrels forged from a single steel piece.
The HNLMS Prins Hendrik der Nederlanden marked the Dutch Navy's first major armored vessel and was equipped with the initial four guns of this type. Numerous sources indicate that the ship was armed with Armstrong artillery. References mentioning guns "manufactured in Newcastle" confirm these were the RML 9-inch Armstrong Guns. Additionally, four smaller ironclads along with ten monitors were outfitted with twin 9-inch Armstrong guns housed within a single turret. The Ever class class, comprising 14 gunboats, each carried a single 9-inch Armstrong gun; notably, the first two vessels in this series were constructed by Armstrong Whitworth.
Within the Spanish fleet, the ironclad Méndez Núñez featured four 9-inch Armstrong guns arranged in a central battery configuration, a setup also found on the central battery ironclad Zaragoza. The central battery ironclad Sagunto was armed with eight such guns, as was the broadside ironclad Vitoria.
Ammunition
Dutch ammunition
The Dutch artillery employed three variants of pointed projectiles for use with the 9-inch Armstrong gun: a standard iron shot measuring 68 centimetres (27 in) in length and weighing 105 kilograms (231 lb), a hardened projectile at 52 centimetres (20 in) and 112 kilograms (247 lb), and a steel projectile sized at 51 centimetres (20 in) with a weight of 109 kilograms (240 lb). Also utilized was an exceptionally large "pointed bullet" (puntkogel), approximately 46 centimetres (18 in) long and weighing 113 kilograms (249 lb), characterized by its cylindrical shape. Furthermore, there existed three types of shrapnel shells, each weighing around 68.5 kilograms (151 lb).
Notes
References
- Armstrong & Whitworth Committee (1866), The Report of the Armstrong & Whitworth Committee, Joseph Thomson & Son, Manchester
- Brassey, Thomas (1882), The British Navy: Its Strength, Resources, and Administration, vol. II, Longmans, Green and Co.
- Brassey, Thomas (1888). The Naval Annual 1887. Portsmouth, England: J. Griffin. OCLC 669097244.
- Douglas, Howard (1851), A Treatise on Naval Gunnery, John Murray, London
- Haakman, J.H. (1872), Handboek over de zee-artillerie voor konstabels en matrozen-kanonniers (in Nederlands), J.C. de Buisonjé, Nieuwediep
- Heald, Henrietta (2011), William Armstrong: Magician of the North, McNidder and Grace Limited, ISBN 9780857160355
- Owen, J.F. (1877), Treatise on the Construction and Manufacture of Ordnance in the British Service, Clowes and Sons
- Swart, Jacob (1869), "VII Iets over het tegenwoordige zware Geschut", Verhandelingen en Berigten Betrekkelijk Het Zeewezen (in Nederlands), XXVIII, Wed. G. Hulst van Keulen
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