Houthulst once had a large forest of more than 4,000 hectares. Today, just 70 hectares remain. During the First World War, the Germans transformed the forest into an impregnable fortress. During the final offensive in September 1918, this bastion was stormed by the Belgian Army. By then, all that was left of the once-proud forest was a few shattered tree trunks. The Belgian military cemetery at Houthulst contains the graves of almost 2,000 soldiers who died in the liberation of the Vrijbos (as the wood is known locally). During the Second World War a launching site for German V-1 rockets was constructed in the forest, but it was never used. Amongst other reminders of the war years are the Drie Grachten (Three Canals) Post in Merkem and the Peace Windmill in Klerken (currently undergoing restoration). This mill served as a German look-out post between 1914 and 1918. On the canal at the Drie Grachten, there is an ecological visitors’ centre on board the longboat ‘Isara’.