BL 9.2 inch Howitzer

Infobox Weapon
name= BL 9.2 inch Howitzer


caption=Australian gunners of 55th Siege Artillery Battery about to load their convert|9.2|in|mm|sigfig=3 howitzer, Western Front, circa. July 1916.
origin= UK
type= heavy siege howitzer
is_ranged=
is_artillery=yes
is_UK=
service=1914 - 1945
used_by= UK and Commonwealth
USA
wars=World War I, World War II
designer=Mk I : Coventry Ordnance Works
Mk II : Vickers
design_date=1913
manufacturer=
unit_cost=
production_date=
number=512
variants=Mk I, Mk II
weight=
length=
part_length=Bore convert|121.5|in|m|sigfig=4 (Mk I)
convert|159.16|in|m|sigfig=4 (Mk II)
width=
height=
diameter=
crew=
cartridge=HE convert|290|lb|sigfig=5
caliber=convert|9.2|in|mm|sigfig=4|sing=on
action=
rate=
velocity=convert|1187|ft/s|m/s|sigfig=3 (Mk I)
convert|1600|ft/s|m/s|sigfig=3 (Mk II) [Hogg & Thurston 1972, page 161, 162 quote convert|1600|ft/s|m/s|sigfig=3 for Mk II in WWI British service. US Army manual May 1920 quotes convert|1500|ft/s|m/s|sigfig=3 Mk II, page 295, 303.]
range=
max_range= convert|10060|yd|m|sigfig=4 (Mk. I); convert|13935|yd|m|sigfig=4 (Mk. II)
feed=
sights=
breech=
recoil=hydropneumatic, variable 23-40 inches (MK I); 20-44 inches (MK II)
carriage=siege carriage
elevation=15° - 55° (Mk I)
15° - 50° (Mk II)Hogg & Thurston 1972, page 161, 162]
traverse=30° L & RThe Ordnance BL 9.2 inch howitzer was a heavy siege weapon, among the largest British artillery pieces in World War I.

History

The origins of a British heavy "siege" howitzer broken down into multiple wheeled loads for transport perhaps lie in the Skoda 9.45-inch howitzer that Britain had bought from Austria in 1900 for trials. Britain decided to develop its own heavy weapon instead, but retained the Skoda transport technique, with the 9.2-inch prototype resulting in 1913. [Clarke 2005, page 33]

The weapon incorporated a sophisticated variable recoil mechanism. Full recoil (40 inch Mk I, 44 inch Mk II [Hogg & Thurston 1972 pages 161-162 for WWI British service; US Army Handbook 1920 Page 295 for US service.] ) was allowed at lower elevation, hence absorbing most of the horizontal (i.e. backward) force. A shorter recoil (23 inch Mk I, 20 inch Mk II [Hogg & Thurston 1972 quote recoil at maximum elevation as 23 inches and 20 inches for Mk I and Mk II respectively in WWI British service; the US Army Handbook of 1920 quotes recoil of 19 inches for both at maximum elevation.] ) was allowed at high elevation where the ground itself could absorb much of the vertical (i.e. downward) recoil force. This prevented the breech from approaching the carriage base.

The weapon was undergoing trials as World War I began, and the prototype, "Mother", was in action in France on October 31 1914. This was soon followed by the production Mk. I.

Mk I's range was relatively limited. On 24 June 1916 the MGRA ("Major-General, Royal Artillery"), the senior Artillery commander in France, Major General Birch, requested among other artillery improvements an increase in range to 15,000 yards "even if an increase of the weight of the equipment is entailed". [Major General Birch (over General Haig's signature), to War Office, 24 June 1916. Letter Quoted in full in Farndale 1986 Annex E, Appendix 1.] This resulted in Mk. II in December 1916 with heavier maximum propellant charge and longer barrel which increased the range to 13,935 yards.

Some went to France early in World War II but their main use was as British coastal defences.

Combat use

It was transported in 3 separate loads - body and cradle, bed, barrel - towed either by heavy horses or Holt tractor. A "holdfast" had to be buried to provide a secure platform, the weapon assembled on top, and a box containing 9 tons of earth further anchored the holdfast in front, to counteract the tendency of the carriage front to lift on firing.

The barrel had to be depressed 3° for loading, as can be seen in the photograph of Australian 55th Siege battery.

One disadvantage of the dismantling system was an inability to fire directly from the travelling carriage the way the convert|8|in|mm|sigfig=3|sing=on howitzer could. In addition the time required to bring the weapon into action was increased. However the stability of the siege mounting made it "the most accurate of heavy howitzers". [Farndale 1986, page 139]

The gun was used to demolish deep fortifications and enemy batteries. GHQ considered howitzers "par excellence the counter-battery weapon for destructive purposes, owing to the advantages it possesses over the gun in accuracy and its ability to deliver its shell at very steep angles of descent". But the same document estimated that even for the 9.2 a minimum 60 rounds "will be required to effect the complete destruction of a single well-protected gun pit". [Counter-Battery Work, page 16]

US service

Bethlehem Steel was already manufacturing 9.2-inch howitzers for Britain, prior to the US entry into World War I in April 1917. The order was expected to be completed by July 1917, as British manufacturing capacity rapidly increased and in fact became capable of export. The US government ordered 100 from Bethlehem and 132 from Britain to equip the US army building up in France. Sevellon Brown states that in fact Bethlehem could not meet the US order but that 40 were delivered from Britain by the end of the war.

The US Ordnance manual of 1920 describes its current stock of Model of 1917 (Vickers Mk I) and Model of 1918 (Vickers Mk II) as being built both in Britain and USA. [Handbook of artillery, United States. Army. Ordnance Dept, May 1920. Page 288] The US-built guns may have been British orders to Bethlehem which were redirected to the US army.

Average barrel life of Mk I was estimated from combat experience at 8,300 rounds, while the life of the higher-velocity Mk II barrel was estimated at 3,500 rounds. [Handbook of artillery, United States. Army. Ordnance Dept, May 1920, page 286]

Brown describes the US acquisition of the 9.2 as based mainly on the need at the time to utilize immediately-available manufacturing capacities, and that acquisition of a howitzer based on the French Schneider 240 mm Howitzer for its super-heavy artillery was the main US goal.Brown 1920, Page 68-69] This view is supported by the 1920 US Ordnance manual which describes the 240 mm howitzer as far superior to the 9.2. [Handbook of artillery, United States. Army. Ordnance Dept, May 1920. Page 300]

Image Gallery

ee also

*List of artillery#Siege howitzers and guns

Notes

References

* [http://cgsc.cdmhost.com/u?/p4013coll9,168 "Counter-Battery Work" GHQ Artillery Notes No. 3 February 1918. Redistributed by US Army War College April 1918.] Provided online by Combined Arms Research Library
*Sevellon Brown, [http://www.archive.org/details/storyofordnancei00browrich "The story of ordnance in the World War". Washington, James William Bryan Press, circa. 1920.]
*Dale Clarke, [http://www.ospreypublishing.com/title_detail.php/title=S7883 British Artillery 1914-1919. Heavy Artillery. Osprey Publishing, Oxford UK, 2005]
*General Sir Martin Farndale, History of the Royal Regiment of Artillery. Western Front 1914-18. London: The Royal Artillery Institution, 1986
*I.V. Hogg & L.F. Thurston, British Artillery Weapons & Ammunition 1914-1918. London: Ian Allan, 1972
*United States. Army. Ordnance Dept, [http://www.archive.org/details/handbookofartill00unitrich "Handbook of artillery : including mobile, anti-aircraft and trench matériel", May 1920.] See "9.2-Inch Howitzer Matériel (Vickers)" Pages 283-299

urviving examples

* is preserved on a production Mk. I siege carriage at the [http://london.iwm.org.uk Imperial War Museum, London.]
*Mk I used by the AIF is on display at the [http://www.awm.gov.au Australian War Memorial, Canberra]

External links

*Douglas T Hamilton, [http://www.archive.org/details/highexplosiveshe00hamirich "High-explosive shell manufacture; a comprehensive treatise". New York: Industrial Press, 1916. Ch. VII : Specifications and manufacturing method for British 9.2 inch howitzer shell.]