| BL 12-inch howitzer | |
| Origin: | United Kingdom |
| Type: | Heavy siege howitzer |
| Is Artillery: | yes |
| Is Uk: | yes |
| Service: | 1916–1945 |
| Used By: | UK and Commonwealth |
| Wars: | World War I, World War II |
| Designer: | Vickers |
| Manufacturer: | Vickers |
| Number: | 14 (Mk II); 43 (Mk IV) |
| Variants: | Mk II, Mk IV[1] |
| Part Length: | 160inches (Mk II) 207.6inches (Mk IV)[2] |
| Cartridge: | HE 750lb |
| Caliber: | 12inches |
| Max Range: | 11340yd (Mk II) 14350yd (Mk IV) |
| Recoil: | Variable hydropneumatic |
| Carriage: | siege carriage |
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.[3] 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.