[First] Army area : secret, map no. 4, First Army R.E. supply system; First Army railways, [January 1918]
Series Number Id: UNKNOWN. Sheet number: part of sheet 36. Edition number: 5. Grey base map of whole First Army area, from Ploegsteert in the north to Arras in the south, and as far west as Hesdin. "Reference" in black and red overprint. "[1st] Field Survey Co. R.E. 5643 [numbers crossed out with black overprint and followed with] 5924 [crossed out with red overprint and replaced with] 5945.", Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC22; envelope_number: 691.