Series Number Id: UNKNOWN. Sheet number: part of sheet 36. Secret First Army railway map, May 1918. At head of map in black overprint, "Secret. Railways 15-5-18." "[First] Field Survey Co., R.E. 6066." Grey detail and squaring. Includes "Reference" to normal gauge, light railway, and metre gauge., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC23; envelope_number: 704.
