wwI

The Medium Mark A Whippet was a British tank of the First World War. It was intended to complement the slower British heavy tanks by using its relative mobility and speed in exploiting any break in the enemy lines. Whippets later took part in several of the British Army's postwar actions, notably in Ireland, North Russia and Manchuria.
This armoured fighting vehicle was intended for fast mobile assaults. Although the track design appears more "modern" than the British Tanks Mark I to V, it was directly derived from Little Willie, the first tank prototype, and was unsprung. The crew compartment was a fixed, polygonal turret at the rear of the vehicle, and two engines of the type used in contemporary double-decker buses were in a forward compartment, driving one track each.
https://en.wikipedia.org/wiki/Medium_Mark_A_Whippet