BL 9.2 inch gun Mk IX–X

Ordnance BL 9.2 inch gun Mk IX, Mk X
Mk X gun at Breakneck Battery on Gibraltar, facing north, January 1942
Type	Naval gun Coast defence gun
Place of origin	United Kingdom
Service history
In service	1899 - 1950s
Used by	Royal Navy Royal Garrison Artillery, Royal Artillery from 1922 Royal Australian Artillery Royal Canadian Artillery South African Artillery Portugal Turkey
Production history
Manufacturer	Elswick Ordnance Company Vickers Beardmores
Variants	Mk IX, Mk X, Mk XIV
Specifications
Weight	Mk IX: 27 tons barrel & breech Mk X: 28 tons
Barrel length	Mk IX: 35 ft 10 in (10.922 m) Mk X: 35 ft 9 in (10.897 m) bore (46.7 cal)
Shell	380 lb (170 kg)
Calibre	9.2-inch (233.7 mm)
Breech	Welin interrupted screw
Muzzle velocity	2,643 ft/s (806 m/s)
Maximum range	29,200 yd (26,700 m)

The BL 9.2 inch guns Mk IX and Mk X were British 46.7 calibres naval and coast defence guns in service from 1899 to the 1950s. They had possibly the longest, most varied and successful service history of any British heavy ordnance.

History

These guns succeeded the 9.2 inch Mk VIII 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).

Mk IX was designed as a coast defence gun, with a 3-motion breech. Only 14 were built, and Mk X introduced in 1900 incorporated a single-motion breech and changed rifling.

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. Mk X was hence the final Mark of 9.2 inch guns in British Commonwealth service.

Design

Breech view of a Mk X gun in 1946

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

Naval service

Royal Navy

Forward gun on HMS Cressy

Mark X guns were mounted on :

• Cressy class armoured cruisers commissioned from 1901
• Drake class armoured cruisers commissioned from 1902
• Duke of Edinburgh class armoured cruisers commissioned from 1906
• King Edward VII class battleships commissioned from 1905
• M15 class monitors M15, M16, M17, M18 from 1915

Greek Navy

4 guns of 45 calibres (414 inches) bore produced by Elswick Ordnance Company were mounted in 2 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 4 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 guns 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 or Straits of Gibraltar, 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 port 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 at April 1918.

Mounting

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 breach 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.

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.

Installation

Each gun mounting was installed on a central cast-steel pedestal in a 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).

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.

Organisation

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.

Increasing range 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.

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.

Deployments

The following table summarises the deployment of 9.2 inch guns. 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.

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
Lough Swilly	Ireland	2	0
Queenstown	Ireland	4	0
Berehaven	Ireland	2	0
Gibraltar	Gibraltar	14	8
Freetown	Sierra Leone	2	2
Hamilton	Bermuda	3	0
Kingston	Jamaica	1	0
Valetta	Malta	16	7
Capetown	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	8	8
Sydney - North Head	Australia	0	2
Sydney - Cape Banks	Australia	0	2
Port Kembla - Drummond Battery	Australia	0	2
Newcastle	Australia	0	2
Fremantle - Rottnest Island	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*

Deployment on railway trucks

Main article: BL 9.2 inch Railway Gun

Mk X gun on Mk II "straight-back" truck

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.

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

At Imperial War Museum Duxford

• Mk X (ordnance only) Firepower!, Woolwich.
• Mk X guns at Lord Airey's Battery and O'Hara's Battery, Gibraltar.
• On Greek cruiser Georgios Averof in Faliron Bay near Athens, Greece.
• Mk X Gun at Imperial War Museum Duxford ex Spur Battery, Gibraltar.

Click on the coordinate links in the following list to view map location and/or satellite image.

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

Near Simonstown three 9.2 inch guns in the Scala Battery :

• 34°10.406′S 18°25.479′E
• 34°10.486′S 18°25.312′E
• 34°10.604′S 18°25.172′E
• 34°10.399′S 18°25.371′E – entrance to underground power station etc

Above Llandudno three 9.2 inch guns in the Apostle Battery :

• 34°0.024′S 18°20.720′E
• 34°0.102′S 18°20.690′E
• 34°0.214′S 18°20.855′E

On Robben Island

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

• 33°48.594′S 18°22.184′E
• 33°48.675′S 18°22.267′E
• 33°48.845′S 18°22.235′E (soon to be restored to full operation?)

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

• 33°54.136′S 18°24.807′E

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

• 29°53.009′S 31°3.044′E
• 29°53.063′S 31°3.151′E
• 29°53.174′S 31°3.036′E

The breech of the Oliver Hill H1 gun

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

• 32°0.422′S 115°31.020′E – H1 Gun (restored)
• 32°0.458′S 115°30.839′E – H2 Gun (awaiting restoration)
• 32°0.428′S 115°30.981′E – entrance to underground power station etc

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 C.R.H..

• 

  Early 51½ lb ½ charge cordite Mk I size 44 & 3¾ cartridge
• 

  1914 60 lb ½ charge cordite MD size 37 cartridge
• 

  Mk IV common pointed shell
• 

  MK VIIA armour-piercing shell, land use
• 

  Mk V capped armour-piercing shell, naval & land use

British World War II ammunition

World War II ammunition was somewhat streamlined, typically with ballistic caps of 4 or 5/10 C.R.H., 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)

• 

  Shell handling at North Head, Sydney, 1944. Note ballistic caps
• 

  Women munitions workers making cordite cartridges, World War II

See also

• List of naval guns
• List of coastal artillery

Bibliography

• Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE
• General Sir Martin Farndale, History of the Royal Regiment of Artillery : Forgotten Fronts and the Home Base 1914-18. London:The Royal Artillery Institution, 1988
• Hogg, I.V. (1998). Allied Artillery of World War Two. The Crowood Press, Malborough. ISBN 1-86126-165-9
• Hogg, I.V. and Thurston, L.F. (1972). British Artillery Weapons & Ammunition 1914-1918. Ian Allan, London. ISBN 0 7110 0381 5
• Maurice-Jones, Colonel K. W. (1957). The History of Coast Artillery in the British Army. Royal Artillery Institution, Woolwich.
• Horner, David M. (1995) The Gunners - A History of Australian Artillery. Allen & Unwin, St Leonards. ISBN 1-86373-917-3
• Nicholson, G.W.L. (1972). The Gunners of Canada The History of the Royal Regiment of Canadian Artillery, Volume II 1919-1967. McClelland and Stewart, Toronto.
• Northling, C.J. (1987). Ultima Ratio Regum Artillery History of South Africa. Government Printer, Pretoria. ISBN 0-621-10217-2
• Tony DiGiulian, British 9.2"/47 (23.4 cm) Mark IX
• Tony DiGiulian, British 9.2"/47 (23.4 cm) Mark X