Updated  14 June 2014

Conversion factors to metric measurement

 Ordnance, Q.F. 3.7-inch How Mk 3 on Carriage Mk 4P

 Picture List

 The 3.7-inch How was designed before WW1 but did not enter service until about early 1917, and was used in Palestine and East Africa with both British and Indian mountain batteries, although the first users were probably the Hong Kong & Singapore battery with the Imperial Camel Corps in Palestine.  Between the wars they were used on the NW Frontier of India and developed a reputation for accurate and consistent shooting.  During the 1930's they were also used in light batteries in regular British infantry divisions.  Designed as pack artillery they could be disassembled and carried by mules or towed by short draught (no limber).  In the 1930's they were further adapted for vehicle towing, the Mk 2P carriage.  During WW2 they had some use in European and African theatres and initially with airborne batteries, being generally but not entirely replaced by 75-mm M1, 3.7-inch How batteries accompanied 1 Cdo Bde across the Rhine at Wesel in 1945.  However, they were most widely used in Burma, mainly by Indian mountain batteries but also by British field and light batteries, and continued to serve on India's NW Frontier.  A few were also used in Guadacanal by RNZA and  New Guinea by RAA.  Production was transferred to India and during WW2 798 carriages and 805 ordnances were manufactured there together with some 2.7 million HE rounds.  A HEAT anti-tank shell was specifically developed and produced for use in Burma.


 3.7 inches

Ordnance length
Bore length

 46.5 inches
11.8 calibres


 28 grooves, 1 in  25 increasing  twist

Chamber capacity

 82 cubic inches









Carriage configuration

 Split trail

Max elevation

  -2.5 to 42.5
Note 1

Top traverse

 20 Left & Right

Platform traverse


Basic Weight

 0.75 tons

Length in action

 11.1 feet

Trunnion height

 2.8 feet

Width at wheel hubs

 4.8 feet

Standard HE Shell

Length (less fuze)

 9.94 inches

Calibre radius head


 Body Diameter


Driving Band Diameter


Weight (incl fuze)

 20 lbs

Explosive Weight

 2 lbs


New Gun MV


RT Max Range

Time of Flight @ Max Range

Probable Error @ Max Range

Approx  Propellant Weight



525 f/s


2,277 yds



0.2 lbs



 588 f/s


2,788 yds



0.3 lbs



 698 f/s


3,641 yds



0.4 lbs



803 f/s


4,560 yds



0.5 lbs



961 f/s


6,000 yds



0.6 lbs



1,115 f/s


6,800 yds



0.6 lbs


Rates of fire






Very slow


 6 to 8





Normal Detachment

6 or 9

Gun Tractor

9 mules in pack transport

Artillery Trailer

 No 23

1st Line Ammo (per gun)



Ordnance Mks were 1 and 3, and Mk 1 had several sub-Mks with differing breech mechanisms and different rifling, and the barrel was in two pieces.  Mk 3 was a single monobloc forging with an integral breech ring.    Carriages went through Mks 1 - 4 British and Mk 2 Indian, Mk 4 was the version for vehicle towing and guns were converted to this Mk. Mks also had different trails and shields   Both pneumatic and wooden wheels were used, the latter being used with mule transport.  There were several different shapes of shield.
Modified versions were also designed and manufactured in South Africa.  190 '3.7-in Howitzer' and 101 '3.7-inch Pack Howitzer', the former seem to have had a one piece monobloc barrel.  Ammunition was also produced in South Africa.

Note 1 - Up to 65 with dug-in trail

Picture List

3.7-inch Howitzer Mk 1 on Carriage Mk 1 - A 'studio' picture, the airpump used to replenish the recuperator has been fitted to the trail.

3.7-inch Howitzer

3.7-inch Howitzer - in action in Burma, probably 451 or 455 Light Bty.

Gun Detachment duties in action:

No 1

Detachment Commander

No 2

Operate breech

No 3

Layer, fire gun

No 4


No 5

Prepare ammunition

No 6


There were 3 additional men in batteries using animal transport.

Equipment Publications:
Range Tables Part 1:
HE, 4 CRH, Charges 1 to 5, 1931.
HE, 4 CRH, Charges 1 to 5, 1939.
HE, 4 CRH, Charge Super, 1942.
HE, 4 CRH, 20 lb, Charges 1 to 5, 1945.
(WO Code 1435)      

HE, Upper register, 20 lb, 1947.
(WO Code 1678)

Gun Drill:
26/Manuals/1391    QF 3.7-inch Mk 1 Howitzer on Mks 1 - 3R Carriage, 1934.
26/Manuals/1664    QF 3.7-inch Mk 1 Howitzer on Mk 4 Carriage (Provisional), 1936.
26/GS Pubs/432    
 QF 3.7-inch Mk 1 Howitzer on Mks 1 - 3R Carriage, 1941.
26/GS Pubs/432    
 QF 3.7-inch Mk 1 Howitzer on Mk 4P Carriage, 1941.

26/Manuals/469    QF 3.7-inch Howitzer Mk 1 on Mks 1, 2 & 3 Carriage, 1930.
QF 3.7-inch Howitzer Mk 1 on Carriage 3.7-inch Howitzer Mks 1, 2, 3 & 4P, 1939.

Maintenance Manual:
WO Code 1450    
3.7-inch Howitzer, Ordnance QF Mks 1, 1/1, 1/2 and 3 on Carriage Mks 1/1, 2/1, 2P, 3/1 and Mks 2, 2/1 Indian, 1946.



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