Series Number Id: UNKNOWN. Sheet number: part of sheet 51. Third Army route map 1916/1917. "1st Printing Coy., R.E. 3rd Army (953)." Area is northern half of Third Army area - Arras in SE corner. Traffic routes in red and blue overprint., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC19; envelope_number: 617.