BL 6-inch Mk VII naval gun

Naval and Heavy Field Gun

Naval gun
Coastal defence gun
Heavy field gun

Place of originUnited KingdomService historyIn service

1901–1972 (Fort Scratchley)
1915–1918 (field use)
1901–1959 (naval use)

Wars

World War I
World War II

Production historyDesignerVickersDesigned1899No. built898VariantsMk VII, Mk VII^v, Mk VIII, Mk XXIVSpecificationsMass

16,875 lb (7,654 kg) (gun & breech)^[a]
25 tons (gun on field carriage)

Length279.2 inches (7.09 m)Barrel length269.5 inches (6.85 m) (44.9 cal)Crew9

Shell weightLyddite, HE, Shrapnel 100 lb (45 kg)^[b]Calibre6 in (152 mm)BreechWelin interrupted screwRecoil16.5 in (419 mm)Rate of fire8 rpm^[c]Muzzle velocity

2,525 ft/s (770 m/s) (light charge)
2,775 ft/s (846 m/s) (heavy charge)^[d]

Maximum firing range

Field carriage Mk. II: 13,700 yd (12,500 m)^[e]
Naval: 14,600 yd (13,400 m) (light charge); 15,800 yd (14,400 m) (heavy charge)^[1]^[f]

Filling weight

Lyddite: 13 lb 5 oz (6.0 kg)
Amatol: 8 lb 14 oz (4.0 kg)
Shrapnel: 874 balls @ 27/lb^[g]

The BL 6-inch gun Mark VII (and the related Mk VIII)^[h] was a British naval gun dating from 1899, which was mounted on a heavy travelling carriage in 1915 for British Army service to become one of the main heavy field guns in the First World War, and also served as one of the main coast defence guns throughout the British Empire until the 1950s.

Background

The gun superseded the QF six-inch gun of the 1890s, a period during which the Royal Navy had evaluated QF technology (i.e. loading propellant charges in brass cartridge cases) for all classes of guns up to 6 in (150 mm) to increase rates of fire. BL Mk VII returned to loading charges in silk bags after it was determined that with new single-action breech mechanisms a six-inch BL gun could be loaded, a vent tube inserted and fired as quickly as a QF six inch gun. Cordite charges in silk bags stored for a BL gun were also considered to represent a considerable saving in weight and magazine space compared to the bulky brass QF cartridge cases.^[2]

Naval gun

The gun was introduced on the Formidable-class battleships of 1898 (commissioned September 1901) and went on to equip many capital ships, cruisers, monitors, and smaller ships such as the Insect-class gunboat which served throughout World War II.^[1]

The Mk VIII in naval service was identical to the Mk VII, except that the breech opened to the left instead of to the right, for use as the left gun in twin turrets.

In World War II the gun was used to arm British troop ships and armed merchant cruisers, including HMS Rawalpindi, which briefly fought the German 11 in (280 mm)-gunned battleships Scharnhorst and Gneisenau in November 1939, and HMS Jervis Bay, which similarly sacrificed herself to save her convoy from the 11 in (280 mm)-gunned cruiser Admiral Scheer in November 1940.

Casemate guns on HMS Kent showing shell damage from the Battle of the Falkland Islands
Gun drill on the troop ship RMS Laconia during World War II

World War I field gun

The Mk VII gun was first used as a field gun in France in 1915. It was initially mounted on an improvised rectangular-frame field carriage designed by Admiral Percy Scott. The carriage was based on a design he had improvised for the 4.7-inch gun in the Second Boer War.^[3] It was a successful carriage, except that it limited the elevation and hence the range. A better carriage which allowed elevation to 22°, the MK II, was introduced early in 1916. This was followed by Mk III, V and VI carriages. The gun was operated by the Royal Garrison Artillery in batteries of four, as were all the larger field guns in World War I.

Following a successful deployment in the Battle of the Somme, the role of the gun was defined as counter-battery fire. They "were most effective for neutralising defences and for wire cutting with fuze 106 (a new fuze which reliably burst instantly above ground on even slight contact, instead of forming craters)". They were also effective for long-range fire against "targets in depth".^[4] The Mk VII was superseded by the lighter and longer-range BL 6-inch Gun Mk XIX which was introduced from October 1916, but the Mk VII remained in service to the end of World War I.

Original Percy Scott field carriage
Firing near Beaumetz-lès-Loges, cutting wire for the Australian advance Second Battle of Bullecourt
Night firing at Vimy Ridge

Coast defence gun

The 6-inch Mk VII gun, together with the 9.2-inch Mk X gun, provided the main coast defence throughout the British Empire, from the early 1900s until the abolition of coast artillery in the 1950s. Many guns were specially built for army coast defence use, and following the decommissioning of many obsolete cruisers and battleships after World War I, their 6-inch Mk VII guns were also recycled for coast defence. During World War I, 103 of these guns were in service in coastal defences around the UK.^[5] Some of these, together with others at ports around the wider British Empire, played an important defence role in World War II and remained in service until the 1950s.

A number of new similar guns with stronger barrels which allowed more powerful cordite charges to be used were manufactured for coast defence during World War II, and were designated 6-inch BL Mark XXIV.^[1]

Bastions C and D of the Keep at the Royal Naval Dockyard on Ireland Island, Bermuda, with 6-inch Mk VIIs
Mk VII with a concrete hood at Fort Nepean in 1943
One of two 6-inch Mk VIIs, and two 9.2-inch Mk Xs, at St. David's Battery, Bermuda, in 2011
Mk VII gun on typical coast mounting at Newhaven Fort
A Mk XXIV gun at Half Moon Battery Pendennis Castle.

Notable actions

In the German raid on Scarborough, Hartlepool and Whitby on 16 December 1914, a notable action was fought by the Durham Royal Garrison Artillery of the Territorial Force at Heugh (two guns) and Lighthouse (one gun) batteries defending Hartlepool. They duelled with the German battlecruisers Seydlitz and Moltke (11 in (280 mm) guns) and Blücher (8.2 in (210 mm)), firing 112 rounds and scoring seven hits. The battlecruisers fired a total of 1,150 rounds at the town and the batteries causing 112 civilians and seven military killed.^[6]

World War I ammunition


Mk III 23 lb (10 kg) Cordite MD Cartridge	Mk IV Common lyddite shell	Mk VIIA Common lyddite naval shell	MK XIIA QNT Common lyddite naval shell with night tracer	Mk IX Shrapnel shell	Mk XVI HE shell

Surviving examples

At the Royal Artillery Museum Woolwich, London.
A coast defence gun at Newhaven Fort, Sussex, UK
A gun mounted on the 1904 coast defence emplacement at New Tavern Fort, Gravesend, UK
2 coast defence Mk 7 guns at Fort Dunree, Lough Swilly, in County Donegal, Ireland
St. David's Battery, St. David's Head, St. David's Island, Bermuda. Two Mk VII RBLs, built by Vickers, on Central Pivot Mk II mounts.
Fort Scratchley, Newcastle, New South Wales, Australia. 2 guns dating from 1911. Decommissioned in 1965 and placed in a nearby park. Moved back to their original mounts in 1978 after the Fort became a museum. Both were restored in 1992 by the Fort Scratchley Historical Society and are capable of being fired on special occasions for ceremonial and saluting purposes.
Fort St. Catherine's, St. George's Island, Bermuda 6-inch BL Gun Mk VII Gun, built by Vickers, on Central Pivot Mk II mount.
Warwick Camp, Warwick, Bermuda. Two Mk. VII, built by Vickers, on Central Pivot Mk II mounts. (This is an active military base, and the battery is not accessible by the public. The barrels have reportedly been removed, recently, for remounting on the bastions of the Keep, at the Royal Naval Dockyard, on Ireland Island, which houses the Bermuda Maritime Museum.
Royal Naval Dockyard, Ireland Island, Bermuda. Two Mk VII (L/1029 and RGF) on Central Pivot Mk II, at Bastions C and D of the Keep (fortress) which houses the Bermuda Maritime Museum (there is also one BL 6-inch Gun Mk II and one BL 6-inch gun Mk IV, at Bastion E).^[7]^[8]
A gun on field carriage at The Front Museum, Lappohja, Finland
Fort Ogilvie, Point Pleasant Park, Halifax, Nova Scotia
VSM gun No. 1553 dated 1901 at Princess Royal Fortress, Albany, Western Australia. Obtained from Bermuda during restoration of the site in the 1980s.
Barrel 1489 which fired the first Australian shot of WWI, and 1317 which fired the first Australian shot of WWII at Fort Nepean, Victoria
Mk VII gun dated 1902 at Ile aux Aigrettes, Mauritius
[1] Momi, Vuda, Batteries, Viti Levu, Fiji Islands. One of the barrels is #1266 from 1900
Fort Mitchell, Spike Island, Ireland, 2 Mk VII Guns in casemates on Central Pivot Mk II mounts in good condition and in the process of being restored to full working condition.
Lonehort Fort, Bere Island, County Cork, Ireland- Two 6-inch BL guns are extant- Breech blocks are missing and the guns themselves somewhat rusty, but otherwise appear to be in good condition. The fort was open to the public on 14 and 15 March 2014 for an underground art experience titled "Nest", which took place in the shell rooms below the guns. The shell rooms and hoists are also in good condition.
Coastal Artillery Battery at Outão, Portugal on the mouth of Sado river, protecting Setubal harbour with 3 guns decommissioned in 1998
Two guns dated 1900 and 1902 from HMS Lancaster at Canopus Hill near Stanley Airport, the Falkland Islands, they were refurbished in 2003.^[9]
Three Mk VII (dating 1904, 1914 and 1918) of the Ostenburg battery at the Royal Naval Dockyard, Trincomalee.^[10]
Three Mk VII of the Modara battery at the Rock House Army Camp.
Two Mk VII at Banana, on the Atlantic coast of the Democratic Republic of the Congo. They are out of use since 1960.
One Mk VII taken from Singapore and moved to Tinian as part of a battery of three such weapons, now sits outside the Tinian International airport. This gun fired on the battleship USS Colorado and destroyer USS Norman Scott, on 24 July 1944, causing extensive casualties and damage to both vessels. This surviving weapon bears two distinct gouges on its barrel from American return fire that knocked it out, but is otherwise intact.

Notes

^ 7 tons, 10 cwt, 2 qtrs. 19 lbs with breech fitting, including shot guide.
^ Shell weights given are filled and fuzed i.e. as fired. 100 lb (45 kg) was standard shell weight in WWI. Some earlier shells had slightly higher weights e.g. Mk IV common lyddite shell weighed 101 pounds (46 kg).
^ 8 rounds per minute is the figure given by Vickers. Quoted in Brassey's Naval Annual. 1901. p. 453.
^ 2,525 ft/s firing a 100 lb (45 kg) projectile using 23 lb (10 kg) Cordite MD size-16 propellant; 2,775 ft/s using 28 pounds 10 ounces (13.0 kg) Cordite MD size 26 was the standard naval loading in WWI. Twin mounts and unstrengthened P IV mounts were restricted to the light charge.(Treatise on Ammunition 1915) The original loading was 20 lb (9.1 kg) of the more powerful cordite Mk I size 20, but Mk I caused greater wear.
^ (Clarke 2005, p. 23) quotes 13,700 yd (12,500 m) on the Mk II carriage; (Farndale 1986, p. 130) quotes 12,000 yd (11,000 m) – this is possibly on the Mk I carriage.
^ All figures for 100 lb (45 kg) shell, which was standard in WWI.
^ Figures for WWI field gun.(Hogg & Thurston 1972, p. 243)
^ Mk VII = Mark 7, Mk VIII = Mark 8. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Mark VIII's breech opened to the left and Mark VII's opened to the right, allowing for paired mounts. Guns mounted singly were all the right-opening Mark VII

References

^ ^a ^b ^c DiGiulian, Tony. "British 6"/45 (15.2 cm) BL Mark VII 6"/45 (15.2 cm) BL Mark VIII 6"/45 (15.2 cm) BL Mark XXIV". NavWeaps.
^ Treatise on Ammunition 1915, p. 393.
^ Hogg & Thurston 1972, p. 144.
^ Farndale 1986, p. 158, quoting Artillery Notes. Vol. 4 – Artillery in Offensive Operations. War Office. February 1917.
^ Farndale 1988, p. 404.
^ Farndale 1988, pp. 368–369, 401.
^ "Virtual site map". Bermuda Maritime Museum. Archived from the original on 3 February 2007.
^ C.L. Kimbell; R.D. Zink; T.C. McGovern (February 2014). "Other Surviving North American Seacoast Artillery Weapons" (PDF). American Seacoast Defenses: A Reference Guide. p. 242. Retrieved 22 June 2018.
^ "Stanley Services Refurbish Naval 6inch Guns". Stanley, Falkland Islands: Stanley Service Ltd. Archived from the original on 16 October 2017. Retrieved 15 October 2017.
^ "The defence of Trincomalee and the 6 inch battery at Hood's Tower". victorianforts.co.uk. Retrieved 22 November 2020.

Bibliography

Handbook for The 6-Inch Breech Loading Mark XII Gun (PDF). Admiralty, Gunnery Branch, G. 21117/17. 1917.
Treatise on Ammunition (PDF) (10th ed.). War Office. 1915.
Clarke, Dale (2005). British Artillery 1914–1919. Heavy Artillery. Oxford UK: Osprey Publishing. ISBN 978-1-84176-788-8. Archived from the original on 21 October 2006. Retrieved 26 September 2007.
Farndale, Martin (1986). History of the Royal Regiment of Artillery. Western Front, 1914–18. London: Royal Artillery Institution. ISBN 978-1-870114-00-4.
Farndale, Martin (1988). History of the Royal Regiment of Artillery. The Forgotten Fronts and the Home Base, 1914–18. London: Royal Artillery Institution. ISBN 978-1-870114-05-9.
Hogg, I.V. & Thurston, L.F. (1972). British Artillery Weapons & Ammunition 1914–1918. London: Ian Allan. ISBN 978-0-7110-0381-1.

External links

Wikimedia Commons has media related to BL 6 inch Mk VII naval gun.

Handbook for the 6-inch B. L. guns, marks VII and VII^v (land service). London: His Majesty's Stationery Office. 1911 – via State Library of Victoria.
Gander, Terry (2011). "Twentieth Century British Coast Defence Guns" (PDF). Fortlet. 2. Archived from the original (PDF) on 14 April 2014.
Scott, Percy (1919). Fifty Years in the Royal Navy. London: John Murray – via The Internet Archive.

Links to related articles
v t e British Empire naval weapons of the First World War
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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 I – IV BL 13.5-inch Mk V BL 13.5-inch Mk VI 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-pounder 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 Mk I – III 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-pounder 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

v t e British Empire artillery of the First World War
Armoured vehicle guns	QF 3-pounder Vickers QF 6-pounder Hotchkiss QF 6-pounder 6 cwt
Infantry guns	1.59-inch breech-loading Vickers Q.F. gun, Mk II
Field artillery	BL 12-pounder 6 cwt QF 12-pounder 8 cwt QF 12-pounder 18 cwt QF 13-pounder BL 15-pounder BLC 15-pounder QF 15-pounder QF 18-pounder QF 4-inch gun Mk III BL 4-inch gun Mk VII QF 4.5-inch howitzer
Medium & heavy artillery	QF 4.7-inch gun BL 5-inch howitzer BL 5.4-inch howitzer BL 60-pounder gun BLC 6-inch siege gun BL 6-inch gun Mk VII BL 6-inch gun Mk XIX BL 6-inch 26 cwt howitzer BL 6-inch 30 cwt howitzer BL 8-inch howitzer Mk I – V BL 8-inch howitzer Mk VI – VIII
Siege artillery	BL 7.5-inch Mk III naval gun BL 9.2-inch howitzer BL 9.2-inch Mk X naval gun BL 12-inch howitzer BL 12-inch Mk X naval gun BL 15-inch howitzer
Mountain artillery	RML 2.5-inch mountain gun BL 10-pounder mountain gun BL 2.75-inch mountain gun QF 2.95-inch mountain gun QF 3.7-inch mountain howitzer
Mortars	Garland trench mortar 3-inch Stokes mortar Vickers 1.57-inch mortar 2-inch medium mortar Newton 6-inch mortar 9.45-inch Heavy Mortar
Smoke and chemical weapons	4-inch Stokes Mortar Livens Projector Livens Large Gallery Flame Projector
Anti-aircraft guns	QF 1-pounder pom-pom QF 2-pounder "pom-pom" Mk II 75 mm AA gun QF 12-pounder 12 cwt QF 13-pounder 6 cwt QF 13-pounder Mk IV QF 13-pounder 9 cwt QF 3-inch 20 cwt QF 18-pounder QF 4-inch Mk V
Coastal artillery	QF 12-pounder 12 cwt QF 4-inch naval gun Mk I – III BL 6-inch Mk VII naval gun BL 9.2-inch Mk IX – X naval gun RML 9-inch
Railway guns	BL 9.2-inch railway gun BL 12-inch railway gun BL 12-inch railway howitzer BL 14-inch railway gun

v t e British Commonwealth artillery of World War II
Tank guns	QF 2-pounder QF 3-pounder QF 6-pounder QF 75 mm QF 3-inch howitzer QF 17-pounder 77 mm HV QF 95 mm howitzer
Anti-tank guns	QF 2-pounder QF 6-pounder QF 17-pounder
Field guns and howitzers	75 mm Gun M1917 QF 18-pounder 25-pounder Gun-Howitzer 25-pounder Short QF 4.5-inch howitzer
Medium and heavy guns and howitzers	BL 4.5-inch medium field gun BL 60-pounder gun BL 5.5-inch medium gun BL 6-inch howitzer BL 6-inch gun Mk XIX 155 mm Long Tom BL 7.2-inch howitzer BL 8-inch howitzer BL 9.2-inch howitzer 240 mm howitzer M1
Mountain guns	75mm Pack howitzer M1 3.7-inch mountain howitzer
Mortars	SBML 2-inch mortar ML 3-inch mortar ML 4.2-inch mortar
Anti-aircraft weapons	Z Battery 20 mm Oerlikon 20 mm Polsten QF 1½-pounder Mk III QF 2-pounder naval gun Bofors 40 mm QF 3-inch QF 3.7-inch QF 4.5-inch Mk II QF 5.25-inch Mk II
Coast defence	QF 6-pounder 10 cwt QF 12-pounder QF 4.7-inch Mk I–IV BL 6-inch Mk VII & Mk XXIV BL 7.5-inch Mk VI BL 8-inch Mk VIII BL 9.2-inch Mk X BL 14-inch Mk VII BL 15-inch Mk I
Railway artillery	BL 9.2-inch Mk XIII railway gun BL 12-inch Mk V railway howitzer BL 13.5-inch Mk V railway gun BL 18-inch railway howitzer