The Fort Immerhof was constructed in between 1930 and 1935. The Fort is insofar peculiar, as its entire construction was carried out in open air and covered up with earth after completion. Construction took three years with total costs of 30,000 Francs (then). To withstand even 305mm shells, the walls were 2,5m thick. To protect the crew from falling debris and concrete during an attack, an inner encasement was installed.

Due to the brilliant impermeability until today, the Fort is in a very good condition. Thanks to the perfect hermetic insulation, both of the 120 kW Diesels are completely functional. The Fort has two combat blocks with twin MGs, one artillery block with a 81 mm mortar and only one entry block. The blocks are connected by 250m corridors.

Its crew of 193 troopers and 5 officers were having a quiet war. There was some artillery shelling from the 10. may onwards, but no close combat offensives. The function of the Fort was to ensure fire continuity between the Fort of Molvange in the west and the Fort of Soetrich in the east as well as securing the blind angles of the sector.

On june, 22., 1940, day of the armistice, the Fort surrendered without having fired one shot. he French army occupied and maintained the Fort after the war until 1968, remaining vacant until 1974, when the town council of Hettange-Grande took it over and opened it to the public.