The Fort of Hackenberg can be found close to the village of Veckring, 43km south-east of Metz. Its impressive size of 160 hekcares and 19 blocks make it the biggest and most improtant Fort of the Maginot Line. The electric power station inside the Fort had four AC-Diesels with a power of 380kW each. It would have been able to supply a town of 10,000 inhabitants. Hackenberg was self-reliant for three months.
Built from 1929-35, it accomodated 1140 soldiers and 45 officers. A tunnel system of 10km extended over multiple floors. To transport ammunition and crew, the Fort had a 3,5 km long electric railway system with a current collector of 600V. The control mode (electric/manual) could be changed at the station of the Fort. Inside the mountain, at a depth of 96m, barracks, hospital and two kitchens can be found. One kitchen was for the troopers, the other one for officers only. Food was delivered by train. In a nische next to the tracks, there even is a small chapel. In 1975, a subterranean military museum was established. Two men shared one bed in the comfortable 13°C interior. Hier kommt keiner durch - No one comes through The 17 combat blocks of the Fort were capable of firing four tons of munitions per minute.

Entire armament of the turrets as follows:

      nine 75mm cannons

      five 135mm grenade launchers/ul>
            four 81mm mortars in rotatable turrets
            thirty-two 50mm mortars in rotatable turrets
            seven 37mm anti tank cannons
            twenty-seven heavy MG
            one hundred and twenty-eight grenade launchers and MG
            eight rotatable turrets

Combat block 11 is situated 96m higher than the train running underneath it and can be reached via an electric elevator or stairs. The rotatable turret (entire weigth: 170t) with its two 135mm cannons is still functionable, which will be demonstrated to the visitors (inside and outside). Firing range was 5,6km Two men were necessary to operate it. The turret is (like all of the rotatable turrets) 360° turnable, its cannons were capable of firing 7-8 shells per minute. To avoid over-heating, the cannons fired alternately. A small elevator transported the grenades from the lower level of the turret up to the „chambre de tir“, where the gunner loaded and fired the cannons. 

Munition depot M1 is the largest one in Hackenberg, holding shells for the 84mm mortar, the 75mm howitzer and the 155mm grenade launchers.

Next to the munition depots, large plated doors can be seen. Each of them weighs 8 tons and protected the crew against shock waves. The crew of the Forts were very much afraid of such explosions in munition depots, because normal case saw the entry doors closed, so possible shock waves could not escape but instead, came back and threatened to destroy the tunnels and bend the doors. To allow the shock waves to spread and diffuse, niches and recesses were included during the construction.

There were no attacks on this main Fort of the Maginot Line nor any battles in the adjacencies until the armistice in 1940. When the crew learned about it, theyrefused to give up the Fortwithout a struggle. Only one week later, (2. july) they finally surrendered and were lead away as POW on the 4. of july.
The German Army occupied the Fort until 1944, when American bombardment forced them to retreat. Before doing so, they planted a bomb. The explosion of it destroyed some parts of the munition depots and bent an above mentioned plated door weighing 8 tons.

Until 1975, the Fort remained vacant. Since then, the Association des Amis des Ouvrages Fortifiés de la Région THIONVILLE (Association of Friends of Forts in the region of Thionville) maintains the Fort and keeps it open to the public.