Series Number Id: GSGS 3383. Sheet number: part of sheet 57. Combined situation map, German retirement and Battle of Arras, 1917. At head of map in blue overprint: Combined situation map no. 1 [number crossed out in pencil, and corrected to 2] First, Third & Fifth Armies. "Ordnance Survey, January 1917." Grey detail, water blue. In blue overprint: British Front Line evening of 11-4-17 in solid blue; British Front Line evening of 16-3-17 in pecked blue., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC16; envelope_number: 462.