Anglo-American project of heavy tank, intended to be the common tank of the allied armies. Designed in 1917, it was the result of experiences matured during the First World War, but the armistice prohibits any operational verification of its qualities. However, it was produced in 125 copies in both the USA (by the Rock Island Arsenal) and Great Britain (by the North British Locomotive Company), in 1918-1920. The British never allocated their Mark VIIIs to a tank unit; a single vehicle survives at the Bovington Tank Museum.