BL 9.2-inch Mk IX – X naval gun

The BL 9.2-inch Mk IX and Mk X guns[note 1] were British breech loading 9.2-inch guns of 46.7 calibre, in service from 1899 to the 1950s as naval and coast defence guns. They had possibly the longest, most varied and successful service history of any British heavy ordnance.

Ordnance BL 9.2-inch gun Mk IX, Mk X
Mk X gun facing north at Breakneck Battery on Gibraltar January 1942.
TypeNaval gun
Coast defence gun
Place of originUnited Kingdom
Service history
In service1899–1950s
Used byRoyal Navy
Royal Garrison Artillery, Royal Artillery from 1922

Royal Australian Artillery
Royal Canadian Artillery
South African Artillery

Production history
ManufacturerElswick Ordnance Company
VariantsMk IX, Mk X, Mk XIV
MassMk IX: 27 tons barrel & breech
Mk X: 28 tons[2]
Barrel lengthMk IX: 35 ft 10 in (10.922 m)
Mk X: 35 ft 9 in (10.897 m) bore (46.7 cal)[2]

Shell380 lb (170 kg)[2]
Calibre9.2-inch (233.7 mm)
BreechWelin interrupted screw
Elevation0° to 15° (on Mark V Barbette mount)
Traverse360° (on Mark V Barbette mount)
Muzzle velocity2,643 ft/s (806 m/s)[3]
Maximum firing range29,200 yd (26,700 m)[4]


These guns succeeded the BL 9.2-inch Mk VIII naval gun and increased the bore length from 40 to 46.7 calibres, increasing the muzzle velocity from 2,347 feet per second (715 m/s) to 2,643 feet per second (806 m/s).

The Mk IX was designed as a coast defence gun, with a three-motion breech. Only fourteen were built and the Mk X, introduced in 1900, incorporated a single-motion breech and changed rifling, succeeded them. As coastal artillery, the Mk X remained in service in Britain until 1956, and in Portugal until 1998. 284 of the Mark X version were built by Vickers, of which 28 examples are known to survive today, all except one fitted on barbette mounts. One in Cape Town is on a disappearing mount.

The 9.2-inch Mk XI gun introduced in 1908 increased the bore length to 50 calibres in an attempt to increase the velocity still further, but proved unsuccessful in service and was phased out by 1920. The Mk X was hence the final Mark of 9.2-inch guns in British Commonwealth service.

The BL 9.2 also affected the development of radar. Immediately before the second world war, an army team developed a surface-scanning radar to detect enemy ships in the English Channel. By chance, in July 1939 one of these radars was being tested while the 9.2-inch battery at Brackenbury Battery outside Harwich was firing. The radar team noticed odd returns on their displays, and realised that these were due to the waterspouts caused by the shells exploding in the water creating a vertical surface off which the signals reflected. The use of radar to accurately spot the fall of shells was rapidly developed, and was widespread by the war's end.[5]


These were medium-velocity wire-wound guns with Welin interrupted screw breeches.

Royal Navy

Mark X guns were mounted on :

Greek Navy

Four guns of 45 calibres (414 inches) bore produced by Elswick Ordnance Company[6] were mounted in two twin turrets on the Greek cruiser Georgios Averof in 1910, instead of the 10-inch guns mounted on her sisters of the Pisa-class in Italian service. These were similar to the four Vickers 45-calibre export model guns used by Britain as railway artillery on the Western Front in World War I under the designation BL 9.2-inch gun Mark XIV. They fired the same 380-pound shell using the same 120-pound cordite charge as the British service Mk X gun, and it may be assumed that its performance was very similar.

British coastal deployments

These were 'counter-bombardment' guns designed to defeat ships up to heavy cruisers armed with 8-inch guns. They were deployed in the fixed defences of major defended ports throughout the British Empire until the 1950s.

Their role was to defeat enemy ships attacking the ships in a port, including warships, alongside or at anchor in the port. However, where guns covered narrows, such as the Dover Straits, the Straits of Gibraltar, or the Narrows of Bermuda, they also had a wider role of engaging enemy ships passing through the straits. Normally deployed in batteries of two or three guns, a few major ports had several batteries positioned miles apart.

There were several marks of mountings and a battery had extensive underground facilities in addition to the guns visible in their individual gun-pits. Together with the 6-inch Mk VII, they provided the main heavy gun defence of the United Kingdom in World War I. 3 Mk IX and 53 Mk X guns were in place as of April 1918.[7]


The Mounting Barbette Mark V (the original mounting with Mark IX and X guns) gave a maximum elevation of 15 degrees, and maximum range of 21,000 yards. This and some modified to Mark VI (30 degrees and 29,500 yards) were manually powered, the projectile and propelling charge were manually hoisted to loading level, the projectile manually loaded and rammed, and traverse and elevation were by handwheels. There was an elevated platform around the breech area for the gun detachment commander (No 1) and some detachment members, and a Gun shield to the front. The ordnance and mounting together weighed some 125 tons, they were well balanced and the handwheels needed very little effort to move the gun.[8]

However, the Mark VII mounting appeared in the 1930s and in 1939 a simplified version, Mark IX. Both were hydraulically powered and the platform was enclosed in a roofed gun house with three sides (and rear with Mark IX). The hydraulics meant that both projectile and propelling charge could be hoisted in a single load. With Mark VII and IX the maximum elevation was increased to 35 degrees to give a maximum range of 36,700 yards.[8]


Each gun mounting was installed on a central cast-steel pedestal in an open concrete gunpit 35 feet in diameter and 11 feet deep. The gun and mounting weighed 125 tons. A very narrow gauge rail track was embedded around the gunpit floor. A trolley was manhandled around the track between the two ammunition lifts (one for projectiles, one for propelling charges) and the rear of the gun (this position varied depending on where the gun was pointed).[8]

Below the gun pit were the separate ammunition bunkers for projectiles and shells with direct access to the ammunition lifts. These bunkers had an access road leading to them for ammunition re-supply. The guns presented only a very small target above ground level, guns and gunpits were camouflaged.


Two or three guns comprised a named battery position with the guns manned by a Heavy Battery. For example, in 1940 Madalena and Bijemma batteries, both with 9.2 in Malta were manned by 6 Heavy Battery RA of 4 Heavy Regiment RA.[9]

Increasing ranges led to new centralised control arrangements. Fortress observation posts, equipped with rangefinders and directors were sited 4000 – 10,000 yards apart to give observation of all the sea area within range. They reported enemy ship bearings and distances to the ‘fortress plotting centre’ (FPC) where the attackers' positions and courses were plotted, converted to coordinates and then assigned as targets to batteries by the fire commander. The details were telephoned to batteries. The battery plotting room used a coordinate converter to turn the coordinates into bearings and elevations and transmitted them to the guns where pointers were matched by changing the guns’ traverse and elevations.[10]

The observers also reported fall of shot relative to the targets, the FPC used an encoder to convert these into a clock code, which the battery converted to its left/right, add/drop corrections. Various types of radars integrated into the fire command soon became widespread in WW2 and enabled effective night engagements.[10]


The following table summarises the deployment of 9.2-inch guns.[11][12][13][14] It is possible that some 1914 guns were still the older marks. * indicates deployment was not completed until after 1940. A third Canadian battery was not completed until after World War II. The three guns in Bermuda remained in battery through the Second World War (and are still in situ), but were not actively utilised.

Ports defended by 9.2-inch guns
Port Country/territory World War I World War II
Dover United Kingdom 5 6
Medway & Thames United Kingdom 4 2
Harwich United Kingdom 0 2
Tyne United Kingdom 2 1
Tees & Hartlepool United Kingdom 0 1
Humber United Kingdom 0 2
Solent United Kingdom 14 6
Portland United Kingdom 6 4
Plymouth United Kingdom 8 6
Milford Haven United Kingdom 4 2
Forth United Kingdom 6 3
Cromarty United Kingdom 3 0
Lough Swilly Ireland 2 0
Queenstown Ireland 4 0
Berehaven Ireland 2 0
Gibraltar Gibraltar 14 8
Freetown Sierra Leone 2 2
St. George's Bermuda 3 0
Kingston Jamaica 1 0
Valletta Malta 16 7
Cape Town South Africa 2 7
Simonstown South Africa 3 3
Durban South Africa 0 3*
Port Louis Mauritius 2
Colombo Sri Lanka 4 2
Trincomalee Sri Lanka 0 2
Singapore Singapore 5 6
Hong Kong Hong Kong 0 8
Sydney – North Head Australia 0 2
Sydney – Cape Banks Australia 0 2
Port Kembla – Drummond Battery Australia 0 2
Newcastle Australia 0 2
FremantleRottnest Island Australia 0 2
FremantleGarden Island[15] Australia 0 2*
DarwinEast Battery Australia 0 2
Halifax Canada 0 3*
Vancouver Island Canada 0 2*
Auckland – Stony Batter New Zealand 0 2*
Auckland – Whangaparaoa New Zealand 0 2*
Wellington – Wrights Hill Fortress New Zealand 0 2*

Portugal has several surviving examples, with live firings as recently as 10 December 1998. The Portuguese refer to these guns as 23.4 cm guns, made by Vickers.[16]

Deployment on railway trucks

In 1916 Elswick adapted a small number of Mk X guns, 2 Mk X variants originally intended for coast defence in Australia, and 4 45-calibre Vickers export guns (under the designation 9.2-inch gun Mk XIV) and mounted them on Mk 3 railway truck mountings for service on the Western Front in France and Belgium.[17]

Belgian coast

From 1917 several Mk X guns were deployed ashore on the section of the Belgian coast still held by the Allies, near Nieuport. They were part of the "Royal Naval siege guns" under the command of Admiral Sir Reginald Bacon, and were used for attacking German heavy gun batteries.

Other deployments

In the 1950s, Canadian guns were transferred under NATO auspices, to Portugal (Azores) and Turkey. It is unclear if any UK guns were also transferred.

Surviving examples

There are ten guns in the surrounds of Cape Town, South Africa :

Near Simon's Town three 9.2-inch guns in the Scala Battery :

Above Llandudno three 9.2-inch guns in the Apostle Battery :

On Robben Island three 9.2-inch guns in the De Waal Battery :

Near central Cape Town one 9.2-inch gun in a unique "disappearing mount" in Fort Wynyard :

On the Durban Bluff, South Africa, three 9.2-inch guns in the Da Gama Battery :

On Rottnest Island, off Fremantle, Western Australia two 9.2-inch guns in the Oliver Hill Battery :

In Portugal's Bateria da Raposa, near Fonte da Telha, three 9.2-inch guns in good condition :

In Portugal one 9.2-inch gun of the original three of the Alcabideche battery, near Cascais is partly preserved, and accessible (but no entry) to pedestrians, in the centre roundabout of the staff and services parking at the back of the new Cascais Hospital (8/2016):(Personal observation)

On the Rock of Gibraltar, three 9.2-inch guns :

In Bermuda, two Mk X guns survive on St. David's Island, on Mark V Barbette mounts, at St. David's Battery, overlooking the Narrows Channel that leads to St. George's Harbour, in Bermuda, as well as to the Royal Naval Dockyard, Bermuda, the Great Sound, Hamilton Harbour, and Murray's Anchorage. The battery forms part of Great Head Park, and there is public access.[18] A third Mk X gun, previously at Fort Victoria on St. George's Island, has been relocated to the Bermuda Maritime Museum at the Royal Naval Dockyard, Bermuda to make way for a hotel development, but as of October 2018 has not been remounted.:[19]

The official opening of the restored De Waal Battery on Robben Island, near Cape Town, South Africa, took place on 4 March 2011. The ceremony involved the unveiling and demonstration of the No 3 Gun of the battery of three "Ordnance BL 9.2in Coast Defence Guns". The gun in question, an "Ordnance BL 9.2in Coast Defence Gun on a Mk VII mounting", has been restored as a moving display, with all the hydraulics working, enabling the turret to be fully traversed through 360°, the gun being elevated to 25° and the loading/ramming mechanism fully operational.

Of the original ninety-eight 9.2-inch guns that did service worldwide during WWII, only about twenty-eight remain. Of these twenty-eight, twelve are in South Africa, the De Waal Battery No. 3 gun being the only gun in the world that has been restored as a moving display. Plans are afoot to restore the nearby Scala Battery at Simon's Town as a static display.[20]

On Western Australia's Rottnest Island the H1 gun and associated underground resources are open to visitors as a static display.

On 10 December 1998 the Portuguese Coast Artillery fired the last shots from the 6th Battery of their "Fonte da Telha" 9.2-inch (23.4 cm) guns. The fate of the several Coast Artillery Regiment batteries and their weapons has not yet been determined, but it is known that it is the intent of the Army to conserve one for the future Museum of Coast Artillery.

British ammunition up to World War I

Shells up to and including World War I were not streamlined, typically having fairly blunt noses of 2 CRH.

British World War II ammunition

World War II ammunition was somewhat streamlined, typically with ballistic caps of 4 or 5/10 CRH, but still retained square bases rather than the tapered type base typical of projectiles for more modern guns in use in World War II. "Super" charges of 124 pounds cordite SC 205 were available, which boosted the muzzle velocity to 2,872 feet per second (875 m/s)[6]

See also

Weapons of comparable role, performance and era


  1. Mk IX = Mark 9, Mk X = Mark 10. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Hence these were the ninth and tenth models of BL 9.2-inch gun.


  1. Official History of the Ministry of Munitions 1922, Volume X, Part 1, page 73. Facsimile reprint by Imperial War Museum and Naval & Military Press 2008. ISBN 1-84734-884-X
  2. Text Book of Gunnery 1902, Table XII Page 336
  3. 380 lb shell, with 103 lb cordite Mk I propellant size 44 (originally) (Text Book of Gunnery 1902), or 120 lb cordite MD size 37 (1914 onwards). Hogg & Thurston 1972, page 165
  4. Hogg & Thurston 1972, page 165
  5. Wilcox, David (2014). Army Radar. Reveille Press. p. 130.
  6. DiGiulian
  7. Farndale 1988, page 404
  8. Hogg 1998 pg 168
  9. Maurice-Jones 1957 pg 256
  10. Maurice-Jones 1957 pg 215
  11. Maurice-Jones, 1957, pgs 219-224, 229, 246, 251, 256
  12. Nicholson, 1972, pgs 448, 453, 468, 480
  13. Horner, 1995, pg 204
  14. Northling, 1987, pg 343-348
  15. "Scriven Battery site (WW2) - Wikimapia".
  17. Hogg & thurston 1972, page 168-169
  18. Admin. "St David's Battery at Great Head Park Bermuda".
  19. "Gun on the move - The Royal Gazette:Bermuda News".
  20. von Zeil, Glenn (24 January 2012). "Robben Island diversifies rich historical attractions by adding restored World War II De Waal Battery". Department of Defence. Archived from the original on 3 December 2013. Retrieved 2 December 2013.


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