A trench system on the Western Front. One of a series of British aerial reconnaissance photographs recording the positions of trenches on the Western Front during the First World War. An intricate trench system zig-zags its way across the fields. An original caption identifies a front line, probably British, intersected by support, reserve and communication trenches, and points out the positions of gun posts and dugouts. Nord-Pas de Calais or Picardie, France, 30 January 1918., Nord-Pas de Calai