The majority of trench maps were to a scale of 1:10,000 or 1:20,000, although trench maps also frequently appeared on a scale of 1:5,000 (maps printed on a large scale such as 1:5,000, were generally meant for use in assaults). In addition, the British army also printed maps on scales smaller than 1:20,000, such as 1:40,000 and 1:100,000, but these maps seldom showed trenches. Therefore, they do not typically count as "trench maps," although by 1918 certain of the 1:40,000 maps did show trenches. As a rule of thumb, the infantry preferred 1:10,000 and the field artillery 1:20,000, with the heavy artillery and staff officers making primary use of the 1:40,000 maps. In the 'Report on Survey on the Western Front 1914-1918', published in 1920, Colonel E.M. Jack wrote " "The 1:20,000 was the map commonly used by the Artillery, and as trenches could be shown on it in sufficient detail to be of use to the infantry it was the most useful scale of all, and the one that could least easily be dispensed with." "Colonel Jack was a key figure in Great War cartography.