Series Number Id: UNKNOWN. Sheet number: part of sheet 51. Third Army route map before the Battle of Arras, 1917. [Drawn by] "1st Printing Coy. R.E. 3rd Army (950)." [Printed by] No 4 Advanced Section A.P.&S.S." "27 2 17" in red overprint. Traffic routes in red and blue overprint. Shows southern half of Third Army area - Arras in NE corner. Used by Major J. C. Thomson MC, OC 20th Siege Battery RGA (8-inch hows)., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC20; envelope_number: 625.