5925194 Wire entanglements in front of the Hindenburg Line near Heninel, 3 May 1917 (lantern slide) by Unknown photographer, (20th century); National Army Museum, London; (add.info.: Wire entanglements in front of the Hindenburg Line near Heninel, 3 May 1917. Lantern slide, World War One, Western Front (1914-1918), 1917. Belts of barbed wire were placed in front of the front-line trenches on the Western Front. They were placed far enough from the trenches to prevent the enemy from approaching close enough to throw grenades in. Sometimes wire entanglements were designed to channel attacking infantry into machine-gun and artillery fields of fire. The wire on the Hindenburg Line was especially thick, at least 20 metres wide in many areas. From a box of 80 lantern slides.); by National Army Museum ; out of copyright.