Military Wiki
Ordnance BL 7.5-inch gun Mk II - Mk V
BL 7.5 inch Mk V guns for HMS Shannon Vickers Works LOC ggbain 19618.jpg
Turrets for HMS Shannon under construction at the Vickers Works, Barrow
Type Naval gun
Coast defence gun
Place of origin United Kingdom United Kingdom
Service history
In service 1905–20
Used by Royal Navy
British India
Wars World War I
Production history
Variants Mks II, II*, II**, III, IV, V
Weight 14½ - 16 tons barrel & breech
Barrel length 375 inches (9,520 mm); (50 calibre)

Shell 200 pounds (90.7 kg)
Calibre 7.5 inches (191 mm)
Muzzle velocity 2,765 to 2,840 feet per second (843 to 866 m/s)[1]
Maximum range 14,200 yards (13,000 m)[2]

The BL 7.5-inch guns Mk II - Mk V[3] were a variety of 50-calibre naval guns used by Britain in World War I. They all had similar performance and fired the same shells.


Mark II

Mark II guns were originally developed to suit India's coast defence requirements. During World War I several reserve guns made for India but still in the UK were employed as coast defence guns in the UK. They were scrapped or sent to India soon after the war.[4]

Marks II*, II**, V

Starboard secondary Mk V battery on HMS Minotaur

These were built and employed specifically as naval guns and were mounted as secondary armament as a heavier alternative to 6-inch guns, on the following ships :

Mark III

Forward port Mk III casemate guns on Swiftsure, Gallipoli 1915

Mk III gun from Swiftsure being transported in Belgium in 1917. Photo by Ernest Brooks.

Mark III guns were built by Elswick Ordnance to arm the battleship Constitución they were building for Chile. Britain acquired them by default when she bought Constitución in 1903 to avoid the risk of the ship being acquired by Russia. Constitución became HMS Swiftsure in British service.

Swiftsure was decommissioned in 1917 and her guns were used for coast defence in Britain, as siege guns on the Belgian coast near Nieuport for attacking German batteries, and on M15-class monitors.

Mark IV

Mark IV guns were made by Vickers for the battleship Libertad they were building for Chile. Britain acquired them by default in 1903 when she bought Libertad together with Constitución. Libertad became HMS Triumph in British service.

Surviving examples

1906 R.G.F. gun on Elephanta Island

See also


  1. Mk II (coast defence) : 2840 ft/second with 62 lb 12 oz cordite MD size 26 (Special for India)(Hogg & Thurston 1972 page 151); Mk II* & V : 2800 ft/second with 61 lb cordite MD size 26 ; Mk III & IV : 2765 ft/second with 54 lb 4 oz cordite MD size 26 (Range Tables for His Majesty's Fleet, 1910 February, 1911) & Treatise on Ammunition 1915.
  2. Mk II coast defence gun. Hogg & Thurston 1972, p. 151
  3. Britain used Roman numerals to designate versions or models ("Mark" abbreviated as "Mk") until after World War II. Hence this articles covers the second through fifth model/version/Mark of British BL 7.5-inch naval guns
  4. Hogg & Thurston 1972, p. 150


External links

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