Merris : position of Artillery Director Stations, 23-7-18
Series Number Id: UNKNOWN. Sheet number: parts of 27, 28, 36, 36a. Artillery survey map; bearing pickets. "Field Survey Battn. R.E. (9356) 15-7-18 [followed with black overprint] (9405) 24-7-18". Title statement and note in black overprint. Gridded grey base map. Signals shown by black numbered dots., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC19; envelope_number: 580.