[note 1] They were designed by Vickers in Britain and produced by all four British artillery manufacturers but mainly by Armstrong and one American company.

They were the equivalents of the German 21 cm Morser 16 and in British service were used similarly to the BL 9.2-inch howitzer but were quicker to manufacture and more mobile.

They had limited service in the British Army in World War II before being converted to the new 7.2 in (180 mm) calibre.

[1] It was 4–5 tonnes lighter than the improvised 8-inch "howitzers" Mks I – V. The Mk VI barrel was of built-up construction and was 14.7 calibres (117.7 inches (2.99 m)) long, with a range of 10,745 yards (9,825 m).

Introduced July 1916, the Mk VII had a longer barrel (17.3 calibres, or 138.4 inches (3.52 m)) of wire-wound construction and increased the range to 12,300 yards (11,200 m).

Early problems of stability on very hard or soft ground became apparent with the Mk VI, leading to the recoil system not functioning correctly.

A Commission went to France to investigate, and a special level "Vickers platform" was adopted, to which the wheels and trail were secured for accurate shooting.

At the end of World War I on the Western Front, Canada had two 6-gun batteries, Australia 1, Britain 37.

The Mark VII howitzer has a muzzle velocity of 1,525 feet per second and maximum range of 12,280 yards and is of British design and manufacture.

A breech ring is shrunk on over the jacket and carries a lug for connecting the gun to the recoil mechanism.

An additional six regiments, three with each type of gun, are described as being nearly ready for the front at the time of the Armistice.

52 weapons were purchased from the British beginning in January 1918; subsequent inventory figures indicate they were in addition to these totals.

In 1933 some of the howitzers' Asbury breech mechanisms were used in developing the 155 mm gun T3, eventually the M1 "Long Tom".

Thirteen of these howitzers were lost in the battles of the summer of 1944; eight of these belonged to Heavy Artillery Battery 4 and were lost at Valkeasaari on 10 June, while the other five belonged to Heavy Artillery Battery 3, located northeast of Lake Ladoga.