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Ordnance BL 13.5 inch gun Mk I - IV
HMS Hood 13.5 inch forward gun turret.jpg
The forward 13.5-inch (343-mm) gun turret of the battleship HMS Hood in the 1890s.
Type Naval gun
Place of origin United Kingdom
Service history
Used by  United Kingdom
Production history
Designer Elswick Ordnance Company
Designed 1880
Variants Mk I, II, III, IV[1]
Weight 67-69 tons barrel & breech[2]
Barrel length 405 inches (10.29 m) bore (30 calibres)

Shell 1,250 pounds (570 kg)[2]
Calibre 13.5-inch (342.9 mm)
Muzzle velocity 2,016 feet per second (614 m/s)[3]
Effective range 12,000 yards (11,000 m)[2]

The BL 13.5 inch naval gun Mk I ("67-ton gun") was Britain's first successful large breechloading naval gun. Mks I - IV[1] were all of 30 calibres length and of similar construction and performance.

United Kingdom service[]

Royal Navy service[]

Aft barbette mounting on battleship HMS Empress of India in drydock at Chatham Dockyard in the 1890s

The gun was designed to match the new large guns of the French Amiral Baudin-class battleships. Development and manufacture occurred very slowly. It was originally intended to equip the Admiral-class battleships,[citation needed] begun in 1880, but delays led to HMS Collingwood being equipped with inferior 12 inch guns and HMS Benbow with the subsequently unsuccessful 16.25 inch guns.

The remaining Admiral-class ships, Anson, Camperdown, Howe and Rodney, were eventually completed in 1889 equipped with four 13.5 inch guns each, in twin barbettes on the centreline at each end of the superstructure.

The guns also equipped the subsequent Trafalgar class laid down in 1886 and Royal Sovereign-class battleships laid down in 1889.

Coast defence service[]

A single Mk III gun was mounted as a disappearing gun for coast defence at Penlee Battery, Plymouth.[4]

Italian service[]

Barbette mounting on Re Umberto

Guns were also sold to Italy to arm the Re Umberto-class battleships Re Umberto, Sicilia, and Sardegna, laid down in 1884 and finally commissioned in 1893 and 1895.

See also[]

Weapons of comparable role, performance and era[]


  1. 1.0 1.1 Mk I = Mark 1, Mk II = Mark 2, Mk III = Mark 3, Mk IV = Mk 4. Britain used Roman numerals to denote marks (models) of ordnance until after World War II. Hence this article covers the first four models of British 13.5 inch guns
  2. 2.0 2.1 2.2 2.3 Text Book of Gunnery 1902, Table XII, Page 336
  3. 1,250 lb shell, with 630 lb Slow-burning Brown Prismatic powder or 187 lb cordite size 44. Text Book of Gunnery, 1902.
  4. Palmerston Forts Society


External links[]

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