Series Number Id: UNKNOWN. Sheet number: [36 SW]. First Army secret defence map. At head of map in red overprint: Secret. "[First] Field Survey Co., R.E. 5741 [numbers crossed out and replaced with blue overprint] 5865." Grey squared base map. German front in red; British front and rear defence lines in red and blue. Includes "Reference" to wire, defended localities [hatched areas], assembly points, and posts.
Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC23; envelope_number: 703.