During First World War (1914–1918) ammunition was used at an unprecedented scale on the Western Front. The unexpected and sudden end of this industrial war led to an accumulation of hundreds of thousand of tons of excess, unused, and obsolete munitions, giving birth to a new challenge: the urgent need to break it down at an industrial scale unseen before. But there was no proper method to destroy ammunition. Chemical compounds forming ammunition were locally massively introduced in the soils and/or groundwater leading to severe contaminations. One site in particular, “Place à Gaz” in the Spincourt Forest, near Verdun exemplifies the history of the post-war weapons demolition, which vanished from collective memory, and the complexities of toxic war heritage. The history of this hazardous war waste reveals the divergence of the valorized war memory promoted in the museums and battlefields of the Great War and the amnesia regarding its toxic heritage of environmental contamination.