Fortified Sector of the Crusnes The Fortified Sector of the Crusnes ( " Secteur Fortifiée de la Crusnes " ) was the French military organization that in 1940 controlled the section of the Maginot Line extending eastwards approximately from Longuyon . The sector roughly follows the valley of the Crusnes river . Crucially , the trace of the Maginot Line in the Crusnes sector is about " behind " the industrial city of Longwy which sits directly against the French borders with Belgium and Luxembourg . The Crusnes sector was one of the strongest Maginot Line sectors . It was attacked in 1940 by German forces in the Battle of France . Despite the withdrawal of the mobile forces that supported the fixed fortifications , the sector successfully fended off German assaults before the Second Armistice at Compiègne . The positions and their garrisons finally surrendered on 27 June 1940 . Following the war many positions were reactivated for use during the Cold War . Three locations are now preserved and open to the public , with a fourth position under restoration . Concept and organization . The sector was originally planned to protect Longwy , with a pronounced bow to the north comprising seven " ouvrages " replacing all but Bréhain . In order from west to east , these were to be the Ouvrage du Bois de Piepe , Ouvrage de Villers - la - Chévre , Ouvrage de Soxey , Ouvrage de la Rédoute , Ouvrage de Longwy , Ouvrage de Ratentout and the Ouvrage de Verbusch . This line was proposed on 24 June 1930 , but was replaced by the more southerly line on 2 August 1930 . The main line of fortifications would have been within one or two kilometers of the frontier , much farther forward than any other place on the Line , and in contradiction to the Maginot Line ' s concept of defence in depth . Construction began in most places in 1930 , and was largely complete by 1935 . Several locations had additional phases planned . " Petit ouvrages " Aumetz , Bois - du - Four and Mauvais - Bois were all planned to be expanded into " gros ouvrages " after completion of the initial plan . Other planned but unconstructed " ouvrages " included the Ouvrage de Bouillon and the Ouvrage de la Cote 143 ( Hill 143 ) , casualties of realignment . The Ouvrage de Rafour was planned to anchor the west end of the line behind Longuyon , but was canceled and replaced by a series of blockhouses as a cost - saving measure . The Crusnes sector was part of the larger Fortified Region of Metz , a strongly defended area between the Ardennes to the west and the Sarre valley to the east . The Metz region was more important during the planning and construction phase of the Maginot Line than it was in the operational phase of the Line , when the sectors assumed prominence . The Fortified Region of Metz was dissolved as a military organization on 18 March 1940 . The SF ( " Secteur Fortifiée " ) Crusnes was itself dissolved in 1940 , becoming the 42nd Fortress Corps ( " 42e Corps d ' Armee de Forteresse ( CAF ) " ) . Command . The Crusnes sector was under the overall command of the French 3rd Army , headquartered at Fort Jeanne d ' Arc at Metz , under the command of General Charles Condé , which was in turn part of Army Group 2 under General André - Gaston Prételat . The 42nd CAF was commanded by General Sivot , then General Renondeau from 27 May 1940 . As the SF Crusnes , it was commanded by Colonel Miserey from 15 September 1939 . The command post was at Briey . The interval troops , the army formations that were to provide the mobile defense for the sector , to support and be supported by the fixed defenses , were under the command of the 24th Corps ( " 24e Corps d ' Armee " ) , General Fougère , commander . The 24th Corps was in turn made up of the 20th , 51st and 58th Infantry Divisions . Artillery support for the sector was provided by the 152nd Position Artillery Regiment ( " Régiment d ' Artillerie de Position ( RAP ) " ) , which controlled both fixed and mobile artillery , commanded by Lt . Colonel Jacob . The 20th ID was made up of Class A reservists , while the 51st and 58th IDs were Class B reserve formations , not considered suitable for significant combat . Description . The sector includes , in order from west to east , the following major fortified positions , together with the most significant casemates and infantry shelters in each sub - sector : Sub - sector of Arrancy . 149th Fortress Infantry Regiment ( " 149e Régiment d ' Infanterie de Forteresse ( RIF ) " ) , Lt . Colonel Beaupuis , command post at Calvaire d ' Arrancy Peacetime barracks and support , in addition to a caserne at Longwy : Sub - sector of Morfortaine . 139th Fortress Infantry Regiment ( " 139e Régiment d ' Infanterie de Forteresse ( RIF ) " ) , Colonel Ritter , command post at Ville - au - Montois Peacetime barracks and support : Sub - sector of Aumetz . 128th Fortress Infantry Regiment ( " 128e Régiment d ' Infanterie de Forteresse ( RIF ) " ) , Colonel Roulin , command post at Serrouville Peacetime barracks and support : History . Battle of France . In February 1940 General Condé decided to protect the exposed city of Longwy , forming the " Position Avancée de Longwy ( PAL ) " , using a combination of hastily - built blockhouses and field units . A series of anti - tank obstacles were built between Longwy and the border , defended by elements of the 58th and 51st Infantry Divisions . Artillery cover was provided by the 75mm gun turret of Ouvrage Fermont , which could cover all of the area except Longwy itself . Two 75mm gun casemates were built between Mexy and Haucourt to cover this gap . Troops of the German 17th Infantry Division attacked the Longwy position beginning 11 May 1940 . The Germans quickly surrounded the city , with German forces in view of the main Maginot Line . The situation declined over the next two days , the reserve divisions performing poorly , and on the 13th General Condé ordered the evacuation of the PAL . The French 3rd Light Cavalry Division ( " 3e Division Légère de Cavalerie ( DLC ) " ) advanced into Luxembourg in an attempt to spoil the attack before it was ordered back to French territory . The division , composed of one motorized regiment and two of horse , attempted to disrupt the German advance into the Longwy salient , but did not attack in sufficient concentration to accomplish much . Condé was content to reorganize behind the Maginot Line . His passivity has been criticized ; the abandonment of Longwy presented a missed opportunity for a counterattack by French forces . By June , faced with the progressive collapse of the French First Army to the west , the interval troops began to pull back to avoid being encircled behind the Maginot Line . Measure A , issued by 3rd Army headquarters , called for the withdrawal of the interval troops on 15 June , protected by the casemates and " ouvrages " . Measure B was the withdrawal of artillery forces from the intervals late that day and into the 16th , protected by the " ouvrages " . Measure C was the withdrawal of all but skeleton forces from the fortifications . The forces left behind were to withdraw themselves by the 18th after sabotaging all equipment and weapons . As the withdrawal was developing , the Germans planned to pierce the Line between Mauvais - Bois and Bois - du - Four on the 14th , but called off the operation . At the same time , the garrisons of the Fortified Sector of Montmédy evacuated ahead of schedule , leaving the Crusnes sector ' s western flank exposed . Ouvrage Ferme Chappy , a two - block " petit ouvrage " , was now the westernmost extant outpost of the Maginot Line . While it was not in itself strong , it was well within the ranges of the guns of Fermont and Latiremont . Although the interval troops had escaped , by the 17th the Crusnes sector had been enveloped by the Germans from the east and west . Retreat was impossible . Through the day on 17 June , two 8 . 89cm anti - tank guns of the German 183rd Infantry Division fired at Fermont ' s Block 4 , breaching it after 160 rounds , but stopping , unaware that they had nearly succeeded in knocking out the position . The damage was repaired overnight . The German 161st Infantry Division took over the next day . Under the impression that morale in the " ouvrages " was low , the division ' s commander , Lieutenant Gneral Hermann Wilck ordered an attack on Ferme - Chappy and Fermont for 21 June . The assaults failed under fire from the two " ouvrages " and supporting fire from Latiremont . Casualties were 46 German dead and 251 wounded , with two French dead , one each at Fermont and Ferme - Chappy . The Germans were allowed to retrieve their dead and wounded under a flag of truce . An assault against Latiremont was cancelled when the army group commander , General Wilhelm Ritter von Leeb ordered all attacks against Maginot fortifications to stop , as a waste of resources . Action between the 21st and the date of the June 25 armistice was limited to sporadic shelling and , on the French side , to firing off ammunition at the Germans before it could be captured . Other German formations carried out harassing attacks on Aumetz and Bréhain , as well as on individual casemates . Moving behind the French lines , the Germans were able to cut telephone lines at easily - identifiable junctions , leaving the " ouvrages " to radio communications . Following the armistice , brief negotiations settled on a formal surrender for the Crusnes garrisons on 27 June . On the morning of the 27th , the French forces marched out of their positions and returned to their peacetime barracks at Doncourt , Morfontaine and Errouville . All positions were left intact for the Germans , with the exception of Aumetz , sabotaged at the order of its commander , Lieutenant Braun . In 1941 Fermont , along with positions in other sectors , was used to produce a propaganda film about the fall of the Maginot Line to the Germans . Bombardments were staged to make it look like the " gros ouvrage " had fallen . In reality , no " gros ouvrage " was captured by German attack . " Môle de Crusnes " . Following World War II , the French military reclaimed the Maginot Line with the aim of renovating and improving it against a possible attack by Warsaw Pact forces . The strongest positions , Fermont and Latiremont , were designated the " môle de Crusnes " ( " breakwater " ) in 1951 and were placed back into service after a period of rehabilitation . Bréhain received much the same treatment , but was attached to the " môle de Rochonvillers " farther east . Lesser positions , such as Mauvais - Bois , Bois - du - Four and Aumetz , were repaired and kept as government property , but were not formally designated as places of defense . After the establishment of the French nuclear strike force , the importance of the Line declined , and maintenance ceased in the 1970s , with most of the casemates and " petit ouvrages " sold to the public . Present status . Fermont , Bois - du - Four and Casemate C2 of Bréhain are operated as museums and are open to the public . The remainder are either privately owned or are military property , abandoned and sealed . The Casemate de Morfortaine may be visited by arrangement with the owner , who seeks to restore it .