At the end of 1915, the war at ground level became a thing of the past and underground warfare began. In order to ease movements between the front and the lines, the principle of a tunnel link was retained.

Eleven tunnels were dug on the German side and thirteen on the french side. From the end of November 1915 to February-March 1916, the german infantetrymen dug out the Kaisertunnel. The main tunnel is 350mm long, expanding to 455m including the adjacent galleries and was used as a connecting tunnel between the Meurissons gully and the front.

This tunnel was used for more than two years. On 24th September 1918, the germans retreated taking all equipment and material before blowing up all exits. Dug out in clay, the Kaisertunnel is testimony to the underground installations carried out by the French and Germans.

Several facilities still remain (first-aid infirmary with an operating block, communications room, power generator...) and can all be seen today.

Nearby the Kaisertunnel lies a historic trail. Created by the O.N.F. (french Forestry Commission), it allows you to discover trenches and tunnels as well as the haute-Chevauchée Ossuary.