The history of the Hennocque quarry pre-dates World War Two and takes its name from the family who operated the quarry for three generations under their family business, Aubin-Hennocque. The current network also includes the Louisette Quarry next door, which was operated by the company Aries. Allegedly, the Germans visited the site in 1938 and introduced themselves as industrialists observing techniques of stone exploitation in France. Much later during the war, the workers concluded that this was a 5th column visit looking for underground sites for use after the occupation of France.
During the Second World War, the German military developed a long-range rocket named A4 / V2 Rocket . The initial rocket development was undertaken at the Peenemünde Army Research Centre in Germany. The research and development took place over more than 10 years between 1930 and 1942; which concluded with the first test flight that took place on October 30, 1942. The V2 rocket is a sizeable object, measuring 14.5m in length, 1.8m in diameter and has a total weight of 14 tons, including 910 Kg of explosive. Work started in December 1942 on the mass production of the A4 rocket, which was subsequently renamed V2 . This name is an abbreviation of “Vergeltungsawaffe 2”, meaning Weapon of Retaliation No. 2. The Todt organization, one of the primary Nazi civil engineer companies, planned for the construction of special concrete works “Sonderbauten” that were intended to produce the rockets. It was decided to construct three types of works: assembly plants, liquid O2 production plants (see Carrière de Caumont) and storage sites. Due to the bombing by the Allied forces, these works were constructed underground where possible for their own protection.After the defeat of France in 1940, the Germans quickly occupied Méry-sur-Oise and incorporated it into their wider V2 plans. When the decision was made to start construction of the V2 storage base, the Aubin-Hennocque company which owned the quarry was seized. The army forcibly recruited workers from the village people, along with experienced quarrymen to undertake the required work. Their are reports that persons that refused were deported to labour camps. One of the first things the Germans did was to install electricity in the quarry to speed up the conversion process; evidence of the electrical installation can still be seen today. After World War 2, this electrical installation was used to mechanise the quarrying of limestone. Further to the electrical installation, the Germans converted part of the quarry to receive V2 carrying trains underground, with a connection to the nearby rail line also being constructed. The underground tunnel is approximately 1.5km long, 8m high and 10m wide and it is protected by blast doors. Further work was carried out in the galleries to allow fo V2 rockets to be moved safely throughout the underground workings The Germans never finished converting the tunnels before France was liberated in 1944.