Fort de Loncin The Fort de Loncin is one of twelve forts built as part of the Fortifications of Liège in the late 19th century in Belgium . It was constructed between 1881 and 1884 according to the plans of General Henri Alexis Brialmont . Contrasting with the French forts built in the same era by Raymond Adolphe Séré de Rivières , the fort was built exclusively of unreinforced concrete , a new material , rather than masonry . The experimental nature of the new material , and the design features of the fort , led to unintended consequences in combat action . Weak concrete made the fort vulnerable to enemy artillery , while poor living conditions reduced the fort ' s ability to operate under fire . The fort was destroyed during World War I in the Battle of Liège , when the fort ' s magazine was hit by a large - calibre German shell , killing most of the fort ' s occupants . The event marked the debut of the Big Bertha howitzer in combat . Relatively few of the dead were recovered ; the site is now a military cemetery . The fort was never re - used . Description . The Fort de Loncin is located about west of the centre of Liège , in the direction of Brussels and Tongeren . The garrison comprised about 500 men . The fort forms an isosceles triangle whose base is long and whose sides measure . A deep by ditch encircles the fort , which is semi - submerged in the landscape . The principal armament was concentrated in the central massif . The ditches were defended in enfilade by 57mm guns in casemates resembling counterscarp batteries , firing at shot traps at the other end of the ditch . The casemate at the point of the triangle was disposed on two levels , allowing action in case the lower level became obstructed . The fort made provisions for infantry sorties onto the surrounding cleared area . With the exception of the Fort de Loncin , the Belgian forts made little provision for the daily needs of their wartime garrisons , locating latrines , showers , kitchens and the morgue in the fort ' s counterscarp , a location that would be untenable in combat . This would have profound effects on the forts ' ability to endure a long assault . Even at Loncin , the service areas were placed directly opposite the barracks , which opened into the ditch in the rear of the fort ( i . e . , in the face towards Liège ) , with lesser protection than the two " salient " sides . The Brialmont forts placed a weaker side to the rear to allow for recapture by Belgian forces from the rear , and located the barracks and support facilities on this side , using the rear ditch for light and ventilation of living spaces . In combat heavy shellfire made the rear ditch untenable , and German forces were able to get between the forts and attack them from the rear . Loncin was the only Liège fort to be provided with mechanical ventilation , allowing gun and sewage gases to be evacuated , and improving its combat endurance until debris blocked the exhaust . Loncin also provided better sanitary arrangements than its neighbors . The Brialmont forts were designed to be protected from shellfire equaling their heaviest guns : 21 cm . The top of the central massif used of unreinforced concrete , while the caserne walls , judged to be less exposed , used . Under fire , the forts were damaged by 21 cm fire and could not withstand heavier artillery . Armament . The large weapons were all German products , made by Krupp in Essen , but the armor was by Cockerill ( Belgium ) , Ateliers de Creusot ( France ) or Grüson ( Germany ) . The fort was provided with signal lights to permit communication with the neighboring Fort de Lantin and Fort de Hollogne . The guns were fired using black powder rather than smokeless powder , producing choking gas in the confined firing spaces that spread throughout the fort . First World War . In 1914 the Fort de Loncin was one of the last Liège forts to suffer German bombardment . Liège first came under attack on 6 August 1914 . Loncin was massively bombarded for three days from 12 to 15 August , before one of its two magazines , with twelve tons of explosive , blew up . The explosion destroyed the heart of the fort , killing 350 of the 550 - man garrison , their bodies remaining under the wreckage . Loncin was the only fort at Liège that did not surrender . Many of the dead remain in the fort and the site is considered a war grave as well as a museum . The commander of the Liège sector , General Gérard Leman , had chosen the fort as his command post after Germans entered the center of Liège . Following the explosion he was rescued , unconscious or delirious , from the fort ' s ditch and made prisoner . The fort ' s commandant , Victor Naessens , wrote : " Under the effect of this titanic volcano , what remained of the concrete massif was dislocated and the greater part of the garrison was crushed by blocks of concrete , burned alive or asphyxiated . " The 42 cm Big Bertha howitzer , the secret weapon of the German army in 1914 , quickly became widely celebrated . The destruction of the Fort de Loncin was immediately used for propaganda by the Germans , precipitating the surrender of the last two Liège forts , Fort de Flémalle and Fort de Hollogne . The propaganda did much to cement the reputation of the Big Bertha . Lessons of the destruction for the Belgians . The principal reason for the destruction of the Fort de Loncin was that the ammunition magazines had been placed too close to the surface , and had never been upgraded since their construction to deal with improved artillery . Problems with concrete construction also became apparent , as techniques for concrete mixing , placement and construction were still being learned . In particular , a lack of nighttime illumination required that construction be stopped at the end of each day , and a poor understanding of the bonding properties of concrete caused weak points between daily pours of concrete , causing layers of concrete to separate under stress of bombardment or explosion . These faults were cured with the reconstruction of other forts , the use of reinforced concrete , and with the construction of four new forts facing the German frontier to the east of Liége . The largest of these was Fort Eben - Emael , which would play a significant role at the beginning of the Second World War . Commemorative monument . After the war Belgian sentiment of admiration for the fort ' s defenders resulted in a public subscription to erect a monument that King Albert I dedicated on 15 August 1923 . The monument was sculpted by Liège sculptor Georges Petit , and comprises an tower , with two figures at the top representing Roman and Greek warriors rendering honor to the defenders of Loncin . Figures at the base include a woman with her arms spread over a dead soldier at her feet . A separate monument features a tablet with the French inscription " Passant . . . va dire à la Belgique et à la France qu ' ici 550 belges se sont sacrifiés pour la défense de la liberté et le salut du monde " ( " Passer by . . . go say to Belgium and France that here 550 Belgians sacrificed themselves for the defense of freedom and the salvation of the world " ) , attributed to the French general Malleterre , based on the epitaph by Simonides for the Spartan dead at the Battle of Thermopylae . A number of other commemorative monuments were placed at the site , including the " flamme du souvenir " , a figure of a man thrusting a torch from under the earth . Present day . Since 15 August 1914 the Fort de Loncin has been treated as a war grave and place of remembrance . Of the more than 300 dead , the majority remain buried in the wreckage . The remains that have been recovered from the fort have been re - interred in a crypt at the head of the fort . The continuing presence of unexploded munitions was judged by the Belgian army in 2003 to be a potential hazard . In October 2007 , after a project of mine and explosives clearance , 2500 shells , representing 142 tons of munitions , were extracted . During this work 25 bodies were discovered , of which four were identified . All were re - interred on 15 August 2008 .