Cupola of Helfaut

The cupola of Helfaut-Wizernes is old a bunker underground being located on the commune of Helfaut at 5 km of Saint-Omer and built by the army of the Nazi Germany between 1943 and 1944. At the origin this bunker was to be used as a basis of launching with the fused V2; but of many times bombarded by the Allies it never entered in service. Today the Cupola was transformed into museum around three main axes:

the Occupation in the Nord-Pas-de-Calais;
German secret weapons;
the Space conquest during the Cold war.

History

Built mainly in underground in a complex of old careers of flint (dilluvium of Helfaut), of sand (Sand of Landénien) and especially of chalk located close to the towns of Helfaut and Wizernes, in one of the slopes of the Valley of the Aa, under the “Plate of Helfaut” this site was conceived to be an impregnable place of production, storage and launching for the V2 rockets. The site was selected not far from a channel (channel of Noeufossé, coming from the field and being thrown in Aa channeled in Arques and joining Dunkirk), served by several roads and a railway, and with sand and cement available on the spot. Work, started in October 1943, was completed by forced labors of prisoners, under the direction of the Organization Todt which had the responsibility of build “special Constructions quickly” ( “Sonderbauten” ) capable to protect the deployments from the new weapons Nazis. The objective was to quickly build a bunker able to threaten the town of London located at 200 kilometers in the North-West and to replace the predecessor of the Cupola which was the Blockhaus of Éperlecques, this last being proven too vulnerable to the air raid.

Railway tunnels were dug under ground to make it possible the parts of rocket to be brought without risk inside. On the whole more than 6 kilometers of galleries were dug by the Soviet prisoners in order to store the rockets with 42 m of depth. A liquid fuel factory of Oxygène was also built to supplement stock coming from the redeployment of the site of Éperlecques. Underground barracks as of the administrative zones also were dug and reinforced by concrete.

In January 1944, an enormous dome of concrete of a diameter of 71 m and thick of 5 m, weighing approximately 55 000 tons was built. It is this cupola which gave its name to the site.

The engineers Nazis could build this immense reinforced concrete structure by running it directly on the chalk which they had cut beforehand in concave form to make a mould. Once places from there, the chalk located in lower part of the cupola was excavated. Under this space, a second concrete bed was run, thus increasing resistance to the bombs.

Directly under this structure, a vast hexagonal room of 21 m in height was created in order to accommodate the factory of production of the rockets. Once assembled and filled of fuels, V2 were moved outside and put at fire at 50 every 24 hours the theoretical maximum rate.

The French Résistance informed the English of the potential devastator of the Cupola shortly after that its construction started. The first attempts to destroy it however did not take place before March 1944. On this date, the protective dome had already been finished. During five months following, 3 000 tons of allied bombs were released on the installation, sifting the plate of Helfaut of craters, but without success. No bomb reached well the factory of production to the shelter under ground. However a bomb Tallboy of 5 tons damaged chalk surrounding but the dome remained intact.

The site was closed in July 1944 before it was finished and before it fired the least rocket. Hitler ordered its abandonment and the Soviet prisoners were put in trains and returned to Germany. The prisoners were never found.

External bonds

Official site of the Cupola

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