QF 3.7-inch mountain howitzer

Ordnance, QF 3.7-inch Howitzer was a mountain gun, used by British and Commonwealth armies in World War I and World War II, and between the wars.

History
The British Indian Army first requested a modern mountain gun in 1906 to replace the BL 10 pounder Mountain Gun, which had been hastily developed after Second Boer War, but itself had several shortcomings. In particular, the shell weight was seen as too light and the gun lacked any recoil absorber or recuperator, meaning the gun had to be relaid after every shell was fired. However, financial constraints delayed production of the 3.7-inch weapon until 1915. (As a stop-gap, the barrel of the 10 pounder gun was mounted on an updated carriage to produce the 2.75 inch Mountain Gun.

World War I
The 3.7-inch howitzer was first introduced in 1917, and was used in action in that year in Mesopotamia.

The 22nd (Derajat) Indian Frontier Force mountain battery arrived in the East Africa campaign on 18 December 1916, when they relieved the 28th Battery which returned to India. They appear to have re-equipped from the 10 pounder mountain gun to the 3.7-inch howitzer while in East Africa, and first used the new weapon in action in an attack on German positions at Medo, 11 April 1918.



Interwar years
The 3.7-inch howitzer superseded the 2.75-inch mountain gun following World War I. It was used by mountain artillery regiments of the Royal Artillery and the Indian Artillery, and saw much service on the North West Frontier of India between the wars.

World War II
During World War II, the weapon equipped artillery units engaged in the North African Campaign (Tunisia), the Italian Campaign and Burma Campaign, and it was also used in the Netherlands and Ruhr fighting in 1944-45 by units originally destined for mountain warfare in Greece. In the latter theatre, on occasion the gun was dismantled and man-hauled up to the upper floors of buildings to provide close support in urban fighting. A lightened version was used briefly by Airborne formations. At least one example was supplied to the French Army after 1945; it was captured by the Viet Minh and is on display at the Vietnam Army Museum in Hanoi.

During the war the gun, and its ammunition, were also manufactured in other Commonwealth Countries, including South Africa, by the ISCOR (The Iron and Steel Corporation of South Africa), and India. South Africa also produced modified versions of the gun.

The gun was finally declared obsolete by the British Army in 1960, although it had not seen service since 1945. 

Details
The weapon was designed to be broken into eight mule loads, for transport over difficult terrain. The heaviest single section was the interrupted screw breech, which weighed 247 lb. Given an open gun position, a practiced crew could have the guns unloaded from the mules, reassembled and deployed ready for action in barely two minutes. However, the 3.7-inch howitzer's adjustable suspension system allowed it to be deployed on almost any position, even those too uneven or with too steep a gradient to allow field artillery to be sited. The process of removing the howitzer from a position and reloading it onto the gun mules involved much more lifting and securing loads than deploying it, but could be accomplished in three minutes in favourable conditions.

The howitzer had a split trail, the first British weapon to do so, which allowed firing at very high angles (a useful feature in mountainous terrain). It also had a large rectangular shield to protect the crew from small-arms fire, but this was often omitted to save weight. When it was first introduced, the howitzer had two wooden wheels and was light enough be towed by two horses. Later marks had pneumatic tyres and could be towed by any light vehicle, such as the Bren Carrier or jeep.

The propellant casing had five "charge zones", but HE was restricted to no more than Charge 4, to prevent premature detonation of the shell.

Surviving examples

 * Royal Artillery Museum, Woolwich, London
 * 1942 Mk I Barrel on Mk II Carriage, at Imperial War Museum Duxford, UK.
 * Israel Defense Forces History Museum (Batey ha-Osef Museum), Tel Aviv
 * Army Memorial Museum, Waiouru, New Zealand
 * Vietnam Army Museum, Hanoi
 * The War Museum of Athens
 * Example at GEM Homes, Johannesburg South Africa, to be restored shortly (pictures to follow)
 * Example at Lenz Military Base, Johannesburg, South Africa, to be restored soon. (pictures to follow)
 * Outside the Military Police Brigade HQ at Camp Cropper Iraq. (as of Jun 2008)