BL 15-inch howitzer

BL 15-inch howitzer Mk I
In action at Englebelmer Wood, Somme, 7 August 1916
Type	Heavy siege howitzer
Place of origin	United Kingdom
Service history
In service	1915 - 1918
Used by	British Empire
Wars	World War I
Production history
Designer	Coventry Ordnance Works
Designed	1914
Manufacturer	Coventry Ordnance Works
No. built	12
Variants	Mk I
Specifications
Weight	94 tons
Shell	HE 1,450 lb (657.7 kg)
Calibre	15 inches (381.0 mm)
Breech	Welin interrupted screw
Recoil	Hydro-spring 31 inches (790 mm) constant
Carriage	siege carriage
Muzzle velocity	1,117 ft/s (340 m/s)
Maximum firing range	10,795 yd (9,871 m)

The Ordnance BL 15-inch howitzer was developed by the Coventry Ordnance Works late in 1914 in response to the success of its design of the 9.2-inch siege howitzer.

Winston Churchill describes the events that led to the production of this weapon and its role in the subsequent development of the tank in Chapter IV of The World Crisis, 1915. Churchill concluded the howitzer was difficult to employ since it was transported in eight sections on giant caterpillar tractors. When he saw the tractors, he asked if one could be modified to cross a trench while carrying a mounted gun and troops. According to Churchill, The development of test vehicles using this concept contributed to the development of the tank.

The weapon was operated by Royal Marine Artillery detachments of the Naval Brigade, with 1 gun per battery. One gun was sent to Gallipoli but not used there. They were later transferred to the British Army.

It operated successfully where it was needed to destroy deep fortifications on the Western Front, but was limited by its relatively short range compared to other modern siege howitzers. The size and weight made it difficult to move and emplace. No further development occurred after the first batch of 12, and instead Britain continued to develop and produce the 12-inch howitzer and 12-inch railway howitzer.

"Granny" in action during the Third Battle of Ypres, 4 October 1917

howitzer inspected by a British delegation in 1916