Series Number Id: UNKNOWN. Sheet number: part of sheet 36. Festubert - Loos Area, trench map, February 1918 : artillery markings. "Trenches corrected to 6-2-18." "[1st] Field Survey Co., R.E. 5802." British trenches, other defences and trench names blue; German trenches and trench names red. Used by Major J.C. Thomson, RGA (OC 20th Siege Battery - 8-inch howitzers)., Manuscript pencil: British front line after German offensive in April, and British 4-gun/how battery position and blue pencil route markings west of Vaudricourt. OP (?) positions near Gorre, Beuvry, Verquigneul, Labourse, Bracquement., WW1 Trench Map Collection: Box PC21, Envelope 666.