Series Number Id: GSGS 3627 [numbers crossed out with black overprint]. Sheet number: part of sheet 28 and 36. Second Army traffic map, Third Battle of Ypres. "[2nd] F.S. Co. 1377. 27-10-17" in black overprint. "Ordnance Survey, October, 1917." Grey detail; blue water; green squaring; overprint in black and red. "Approximate Army Boundary" chain-dotted black. Roads in black and red., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC19; envelope_number: 593.