Series Number Id: GSGS 3488. Sheet number: 51b and 57c. Battle of Arras, enemy organisation and expoitation map, 1917. The regular sheet 51b with a 4,000-yard deep strip added from sheet 57c (the sheet to the south). "Ordnance Survey, March, 1917." Detail and grid grey; contours brown; water blue. Overprinted with enemy organisation, presumably intended primarily for air, cavalry and tank use, showing railways, headquarters, main defence lines, possible inundations, cuttings, earthworks, embankments and bridges. Enemy organisation green. Principal German trench lines, but not all trenches, in red., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC15; envelope_number: 409.