BL 12 inch Howitzer

BL 12-inch howitzer
12-inch howitzer Mk IV manned by Newfoundland troops training in the UK, 1942
Type	Heavy siege howitzer
Place of origin	United Kingdom
Service history
In service	1916 - 1945
Used by	UK and Commonwealth
Wars	World War I, World War II
Production history
Designer	Vickers
Manufacturer	Vickers
No. built	14 (Mk II); 43 (Mk IV)
Variants	Mk II, Mk IV
Specifications
Barrel length	160 inch (Mk II) 207.6 inch (Mk IV)
Shell	HE 750 lb (340 kg)
Calibre	12 inches (304.8 mm)
Recoil	Variable hydropneumatic
Carriage	siege carriage
Maximum firing range	11,340 yd (10.37 km) (Mk II) 14,350 yd (13.12 km) (Mk IV)

The Ordnance BL 12-inch howitzer was a scaled-up version of the successful BL 9.2-inch siege howitzer.

Following the success of their BL 9.2-inch howitzer, Vickers designed an almost identical version scaled up to a calibre of 12 inches, the Mk II entering service on the Western Front in August 1916. Eight complete equipments are reported as arriving in August 1916 and being in action in France shortly afterwards.

It was similar but unrelated to the BL 12 inch railway howitzers Mk I, III and V produced by the Elswick Ordnance Company at the same time.

The Mk IV was a more powerful version with longer barrel produced from 1917.

Later models were used for British home defence in World War II.

As with other large-calibre weapons, it was operated by the Royal Garrison Artillery in World War I.

The 12-inch was dismantled and transported in six loads mounted on traction engine wheels. It was then reassembled on its static siege mounting on top of a steel "holdfast", with 22 tons of earth in a box sitting on the front of the holdfast in front of the gun, to counteract the kick of firing.

Mk V HE shell, World War I

12 inch shell being loaded