Fort de Koenigsmacker The Fort de Koenigsmacker ( Koenigsmaker , Königsmachern or Kœnigsmacker ) is a fortification located to the northeast of Thionville in the Moselle department of France . It was built by Germany next to the town of the same name in the early 20th century after the annexation of the Moselle following the Franco - Prussian War . The Fort de Koenigsmacker was part of the " Moselstellung " , a group of eleven fortresses surrounding Thionville and Metz to guard against the possibility of a French attack aimed at regaining Alsace and Lorraine , with construction taking place between 1908 and 1914 . The fortification system incorporated new principles of defensive construction to deal with advances in artillery . Later forts , such as Koenigsmacker , embodied innovative design concepts such as dispersal and concealment . These later forts were designed to support offensive operations , as an anchor for a pivoting move by German forces into France . The Feste Koenigsmacker , as Fort de Koenigsmacker was called by the Germans , with Fort de Guentrange and Fort d ' Illange , assured the protection of Thionville against French attack . Positioned to the rear of the principal lines of combat in the First World War , the fort never saw combat in that war , but posed a significant obstacle to advancing American forces in World War II . Description . The Fort de Koenigsmacker is located about to the northeast of Thionville on a hilltop overlooking the salient formed by the Cattenom forest and the northern crossings of the Moselle . It was defended by a garrison of 1180 men . Like the Fort d ' Illange , Koenigsmacker features an armored battery , originally armed with four short 100mm guns in single turrets . Four separate fortified barracks housed troop , with underground galleries connected the battery , barracks , and infantry positions . A ditch , defended by a counterscarp and three caponier s , is located on the south and east sides . The dispersed , un - walled nature of the later " Moselstellung " was a significant innovation . Compared to the French Séré de Rivières system forts of the same era , later German fortifications such as Koenigsmacker were scattered over a large area and enclosed chiefly by barbed wire . While certain individual elements presented imposing walls to an attacker , these walls were not continuous . The dispersed nature is evidenced by the official French name : the " Groupe Fortifié de Koenigsmacker " ( Fortified Group of Koenigsmacker ) . These arrangements were studied and improved upon by the French in the construction of the Maginot Line . Koenigsmacker ' s fairly compact arrangement includes four dispersed fortified barracks built into a hillside so that their rears are shielded by earth , while the tops and fronts are protected by three or four meters of concrete , and are surmounted by parapets . The south barrackst is constructed as an infantry shelter , or " abri " , with no living accommodations . The single battery is similarly constructed and linked to the barracks by underground tunnels . The four 100mm guns in the battery were protected by Schumann turrets and controlled by an armored observation cupola on top of the western barracks . The whole was surrounded by deep networks of barbed wire , which were swept by fire from small perimeter blockhouses , also linked via the tunnel system . The interior of the position was equipped with trenches for infantry . The barracks and batteries were further armored with reinforced concrete and armored windows . A variety of blockhouses and infantry shelters were also built in the intervals between forts . Underground tunnels total in length . Two additional armored batteries were planned for the hill to the northeast of the fort , but were never built . The barracks wer eprovided with central heat , while a central utility plant generated electricity using five 40 hp diesel engines . Operational concept . From 1899 , the Germans viewed Metz as a secure position that could provide an anchor for a pivoting movement into France from the Low Countries . This strategy , which would become known as the Schlieffen Plan , required that the " Moselstellung " deter an advance by French forces into Lorraine while the German forces mobilized . History . Begun in 1908 , Koenigsmacker was incomplete at the outbreak of war in 1914 . It saw no action during World War I , as Thionville remained well within German lines for the duration of the war . With the Compiègne armistice of 1918 , Lorraine was returned to France and the fort became French property . The three Thionville forts became known as the Fortified Group of Thionville . The Fort de Koenigsmacker was integrated into the Fortified Sector of Thionville of the Maginot Line in the 1930s , serving as a sub - sector command post and backing up the newer Maginot " ouvrages " that were built about halfway between Thionville and the border with Luxembourg . The short 105mm guns were replaced by 105mm long guns removed from the German fortifications of Metz . The artillery range was thus increased from to . In 1940 Koenigsmacker was the command post for the 167th Fortress Infantry Regiment ( RIF ) , which manned the nearby Maginot " ouvrages " . During the Battle of France the Thionville area was bypassed and encircled by German forces , with the Maginot and earlier fortifications seeing little action . Koenigsmacker overlooks the crossing of the Moselle at Cattenom . During the Lorraine Campaign of World War II , the U . S . 90th Infantry Division crossed the flooded Moselle early on 9 November 1944 . Fire from Koenigsmacker destroyed bridging equipment and harassed boat - borne troops , but elements of the 358th Infantry Regiment established a lodgement on the east bank and infiltrated the area of the fort before daybreak . The initial American assault took the German garrison , manned by the 74th regiment of the 19th " Volksgrenadier " Division , by surprise , but German resistance quickly became more effective . American combat engineers took over the assault , using explosives to destroy or seal openings and ventilation shafts . The engineers used such a quantity of explosives that they ran out , and had to be replenished by an airdrop . The fort ' s 100mm guns could not be depressed to deal with the close - in attackers , but kept up fire on nearby U . S . formations . By nightfall the Americans had occupied a portion of the fort ' s surface . The next morning , Company C of the 358th attacked from the south , encountering a fortified ditch . Companies A and B meanwhile occupied the fort ' s surface and continued with attacks using demolition charges , while the fort kept up artillery fire on American units trying to pass by the fort . On the 11th much of the fort had been suppressed , but its guns continued to fire . A relief patrol of 145 Germans attempting to relieve the fort was ambushed and captured . On the 12th an assault by G Company of the 358th coincided with a decision by the German garrison to evacuate . Surrounded , the Germans surrendered . More than 300 Germans were captured or casualties , with 111 American casualties . After the war the site remained military property , but was not used . The fort is abandoned and partly stripped . Manning . Under German occupation in 1944 , Koenigsmacker was garrisoned by the 74th Volksgrenadier Regiment of the 19th Volksgrenadier Division . Present status . A proposal has been made to clean up the site and make it accessible with paths and a parking area in the manner of the park at Fort d ' Illange . The site remains dangerous and is not open to the public .