BL 15 inch Mk I naval gun

BL 15 inch Mark I
As mounted on monitor HMS Terror, 1915
Type	naval gun
Place of origin	United Kingdom
Service history
In service	1915-1959
Used by	United Kingdom
Wars	WWI, WWII, Cold War
Production history
Designed	1912
Manufacturer	see text
Produced	1912-1918
Number built	186
Specifications
Weight	100 long tons (100 t)^[1]
Length	650.4 inches (16.52 m)^[1]

Shell	separate charges and shell
Shell weight	1,938 pounds (879 kg)
Calibre	15-inch (381.0 mm)
Recoil	46 inches (1.2 m)^[1]
Rate of fire	2 rounds per minute
Muzzle velocity	2,458 feet per second (749 m/s)
Maximum firing range	33,550 yards (30,680 m) (Mk XVIIB or Mk XXII streamlined shell @ 30°)^[2] HMS Vanguard - 37,870 yards (34,630 m) @ 30°, with supercharges.

The BL 15 inch Mark I succeeded the 13.5-inch (340 mm) gun. It was the first British 15 inch (381 mm) gun design and the most widely used and longest lasting of any British designs, and arguably the most efficient heavy gun ever developed by the Royal Navy. It was deployed on capital ships from 1915 until 1959, and was a key Royal Navy gun in both World Wars.

Design

This gun was an enlarged version of the successful BL 13.5 inch Mk V naval gun, specifically intended to arm the new Queen Elizabeth-class battleships as part of the British response to the new generation of Dreadnought battleships Germany was building during the naval arms race leading up to World War I. The normal slow and cautious prototype and testing stages of a new gun's development were bypassed, and it was ordered straight from the drawing board due to the urgency of the times. In the event it met all expectations and was a competitive battleship main armament throughout both World Wars. According to an American report produced after World War II, the British 15 inch Mk I was the most reliable and accurate battleship main armament of the war, though other guns and mountings had superior individual features.^[3]

Diagram showing gun barrel construction

The barrel was 42 calibres long (i.e., 15 in x 42 = 630 in) and was referred to as "15 inch/42". This wire-wound gun fired a 1938 lb (879 kg) Mk XVIIB shell at a muzzle velocity of 2,458 ft/s (749 m/s).^[2]

The battlecruiser HMS Hood had its Mk I guns in a unique mounting, designated Mk II. Incorporating experience from the Battle of Jutland, the Mk II mounting had a maximum elevation of 30°, thus increasing the maximum range.^[4] In the 1930s a modification of the Mk I mounting, designated the Mk I (N), was introduced for use in those capital ships that were completely reconstructed. The Mk I (N) mounting also increased the maximum elevation from 20° to 30°.^[5] Maximum range in shipboard mountings was 33,550 yards (30,680 m) (30° elevation).^[2] During World War II older battleships with gun elevation limited to 20° were supplied with supercharges to increase their maximum range to 29,930 yards (27,370 m) at 2638 ft/s (804 m/s) using the Mk XVIIB or Mk XXII projectile, while HMS Vanguard could range to 37,870 yards (34,630 m) while using supercharges at a gun elevation of 30°.^[2] Coastal artillery mountings with higher elevations could reach 44,150 yards (40,370 m). The firing life of a 15 inch gun was approximately 335 full charge firings using standard charges, after which it had to be re-lined.^[6]

Usage

In battle

The BL 15 inch Mark I gun proved its effectiveness at the Battle of Jutland in 1916, scoring hits out to 19,500 yards, a record for naval gunnery at that time.^[7]

In World War II the gun was responsible for the longest range shell-hit ever scored by one battleship on another in combat. At the Battle of Calabria on 9 July 1940, HMS Warspite gained a hit on the Italian battleship Giulio Cesare with her first salvo at 26,400 yards.^[8]

Warships

These guns were used on several classes of battleships from 1915 until HMS Vanguard, the last battleship to be built for the Royal Navy, completed in 1946.

Warships with the BL 15 inch Mark I gun:

Queen Elizabeth-class battleships (Five ships with eight guns each - 3 ships converted to Mk I (N))
Revenge-class battleships (Five ships with eight guns each)
Renown-class battlecruisers (Two ships with six guns each - 1 ship converted to Mk I (N))
HMS Hood - battlecruiser (Eight guns, Mk II mounting)
Courageous-class battlecruisers (Two ships with four guns each)
Erebus-class monitors (Two ships with two guns each)
Marshal Ney-class monitors (Two ships with two guns each)
Roberts-class monitors (Two ships with two guns each)
HMS Vanguard - battleship (Eight guns in mountings taken from Courageous and Glorious converted to Mk I (N), with additional armour, designated: Mk I (N) RP12)

Coastal batteries

Two coastal guns ("Clem" and "Jane") were mounted near Wanstone Farm in Kent in the 1940s, and were used extensively for cross-Channel fire throughout the war.
Five guns were mounted in Singapore at Johore battery and Buona Vista Battery in the 1930s.

Animation representing the loading cycle of the Mark I turret for the BL 15 inch Mark I.

Aft guns of HMS Hood trained forward to port, 1926

One of Singapore's 15 inch coastal defence guns elevated for firing

Production

Two 15-inch guns outside the Imperial War Museum; the nearer gun from HMS Ramillies, the other from HMS Roberts.

186 guns were manufactured between 1912 and 1918.^[9] They were removed from ships, refurbished, and rotated back into other ships over their lifetime.

Elswick Ordnance Company, Elswick, Newcastle: 34
Armstrong Whitworth, Openshaw, Manchester: 12.
William Beardmore & Company, Parkhead, Glasgow: 37
Coventry Ordnance Works, Coventry: 19
Royal Gun Factory, Woolwich: 33
Vickers, Son and Maxim, Sheffield: 49

Two guns, one formerly from HMS Ramillies (left gun) and the other originally mounted in HMS Resolution, but later moved to HMS Roberts (right gun), are mounted outside the Imperial War Museum in London.

World War II ammunition


108 lb Cordite cartridge ¼ charge	AP shell Mk XXII BNT	AP shell and cap, as fired by HMS Malaya into Genoa on 9 February 1941	An AP shell in the process of being hoisted to the gun breech, Singapore 1940

References

1 2 3 Ian Buxton, p. 181.
1 2 3 4 John Campbell, p. 25.
↑ Raven and Roberts, p. 411
↑ Raven and Roberts, p. 65
↑ Raven and Roberts, p. 226
↑ Roskill, p. 89.
↑ Burt, p. 73
↑ Burt, p. 133
↑ Ian Buxton, p. 179.

Bibliography

Burt, R. A. (2012). British Battleships, 1919–1939 (2nd ed.). Annapolis, Maryland: Naval Institute Press. ISBN 978-1-59114-052-8.
Buxton, Ian Lyon (1978). Big Gun Monitors. Tynemouth: World Ship Society. ISBN 0-905617-06-1.
Campbell, John (1985). Naval Weapons of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4.
Raven, Alan; Roberts, John (1976). British Battleships of World War Two: The Development and Technical History of the Royal Navy's Battleship and Battlecruisers from 1911 to 1946. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-817-4.
Roskill, Captain Stephen Wentworth (1974). H.M.S. Warspite: The Story of a Famous Battleship. London: Futura Publications. ISBN 0-86007-172-3.

External links

Wikimedia Commons has media related to BL 15 inch Mk I naval gun.

British Empire naval weapons of the First World War

Monitor guns	BL 9.2 inch Mk VI BL 9.2 inch Mk VIII BL 9.2 inch Mk X BL 9.2 inch Mk XII BL 12 inch Mk VIII US 14 inch 45 cal BL 18 inch Mk I

Capital ship main armament	Vickers 10 inch 45 cal EOC 10 inch 45 cal BL 12 inch Mk VIII BL 12 inch Mk IX BL 12 inch Mk X BL 12 inch Mk XI & XII EOC 12 inch 45 cal Mk XIII BL 13.5 inch Mk V EOC 14 inch 45 cal Mk I BL 15 inch Mk I

Armoured cruiser main armament	BL 7.5 inch Mk I BL 9.2 inch Mk X BL 9.2 inch Mk XI

Secondary armament and light cruiser main armament	QF 12 pdr 18 cwt QF 14 pounder Maxim-Nordenfelt QF 14 pounder Mk I & II QF 4 inch Mk III BL 4 inch Mk VII QF 4 inch Mk V BL 4 inch Mk IX BL 5.5 inch Mk I QF 6 inch BL 6 inch Mk VII BL 6 inch Mk XI BL 6 inch Mk XII BL 6 inch Mk XIII-XVIII BL 7.5 inch Mk II - Mk V

Destroyer and small cruiser armament	QF 12 pdr 12 cwt Mk II QF 4 inch Mk III BL 4 inch Mk VIII QF 4 inch Mk IV BL 4.7 inch Mk I

Merchant ship armament	QF 4.7 inch Mk I - IV QF 4.7 inch Mk V*

Submarine guns	BL 4 inch Mk XI QF 4 inch Mk XII

Anti-aircraft guns	QF 2 pounder "pom-pom" Mk II QF 3 inch 20 cwt QF 4 inch Mk V

Light weapons	.303 Vickers machine gun QF 3 pounder Hotchkiss QF 3 pounder Vickers QF 6 pounder Hotchkiss

Torpedoes	18 inch Mk V - VIII 21 inch Mk II 21 inch Mk IV

Mines	Spherical Mk I, II and III Vickers Elia mine Type H mine

Anti-submarine weapons	Type A Depth charge Type B Depth charge Type C Depth charge Type D Depth charge Type E Depth charge Type F Depth charge Type G Depth charge Cruiser Mine 7.5 inch howitzer

Landing guns	QF 12 pounder 8 cwt

British Commonwealth naval weapons of the Second World War

Monitor guns	BL 15 inch

Capital ship main armament	BL 14 inch BL 15 inch BL 16 inch

Heavy cruiser main armament	BL 7.5 inch Mk VI BL 8 inch Mk VIII

Secondary armament and light cruiser main armament	QF 4 inch Mk V QF 4.5 inch QF 5.25 inch BL 6 inch Mk XII BL 6 inch Mk XXII BL 6 inch Mk XXIII

Minesweeper, Sloop, Corvette, Frigate and Destroyer armament	QF 6 pounder 10 cwt QF 12 pdr 12 cwt Mk V QF 4 inch Mk IV BL 4 inch Mk IX QF 4 inch Mk XVI QF 4 inch Mk XIX QF 4.5 inch BL 4.7 inch Mk II QF 4.7 inch Mk IX & XII QF 4.7 inch Mk XI

Submarine guns	QF 12 pdr 12 cwt Mk V QF 3 inch 20 cwt QF 4 inch Mk XII & XXII

Anti-aircraft weapons	Unrotated Projectile Holman Projector 20 mm Oerlikon QF 2 pounder "pom-pom" Mk VIII 40 mm Bofors QF 3-inch 20 cwt QF 4 inch Mk V QF 4 inch Mk XVI QF 4.5 inch QF 4.7 inch Mk VIII

Light weapons	.303 Lewis machine gun .50 Vickers Mk III machine gun QF 3 pounder Vickers

Torpedoes	21 inch Mk VII 21 inch Mk VIII 21 inch Mk X 21 inch Mk XI 24.5 inch Mk I

Anti-submarine weapons	Thornycroft depth charge thrower Hedgehog Squid

Small craft armament	Molins 6 pounder Vickers K machine gun 18 inch torpedo

Foreign-sourced weapons	20 mm Oerlikon 40 mm Bofors 3-inch 23 caliber gun (US) 3-inch 50 caliber gun (US) 4-inch 50 caliber Mark 9 gun (US) 5-inch 51 caliber Mark 8 gun (US) Y-gun depth charge projector (US) Mark 8 torpedo (US)

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