Four à Chaux

Construction of the Four à Chaux took place between 1930 and 1935. The artillery work was built into a mountain approximately 270 meters high, with confined space leading to a compact design. A total of eight blocks were created during this period, with up to 800 workers per shift. A special feature was the electric inclined elevator in the ammunition entrance, which was unique for the facilities in the northeast. The underground tunnel system was comparatively short, at about 1.6 kilometers, which is why electrification of the internal railway was omitted. The fortress included an underground barracks with medical and supply areas as well as technical facilities. In 1938, the work was occupied by troops. On May 20, 1940, the first combat operations occurred when the Four à Chaux opened fire on German patrols.