Fortified Sector of Thionville

169th Fortress Infantry Regiment (169e Régiment d'Infanterie de Forteresse (RIF)), Chef de Bataillon Toussaint, command post at Bois de la Côte

• Ouvrage Rochonvillers, gros ouvrage A8 of nine combat blocks and two entry blocks
• Ouvrage Molvange, gros ouvrage A9 of ten combat blocks and two entry blocks

Peacetime barracks and support:

• Casernement d'Angevillers[7]

168th Fortress Infantry Regiment (168e Régiment d'Infanterie de Forteresse (RIF)), Lt. Colonel Ferroni, command post at Sainte-Marie

• Ouvrage Immerhof, petit ouvrage A10 of three combat blocks and one entry block
• Ouvrage Soetrich, gros ouvrage A11 of six combat blocks and two entry blocks
• Ouvrage Bois-Karre, petit ouvrage A12, single block with no underground facilities
• Ouvrage Kobenbusch, gros ouvrage A13 of seven combat blocks and two entry blocks
• Ouvrage Oberheid, petit ouvrage A14, single block with no underground facilities

Pre-Maginot supporting fortification:

• Fort de Guentrange (Groupe Fortifiée de Guentrange)
• Fort de Koenigsmacker (Groupe Fortifiée de Koenigsmacker)
• Fort d'Illange (Groupe Fortifiée d'Illange)

Peacetime barracks and support:

• Casernement de Hettange-Grande
• Casernement de Cattenom[7]

167th Fortress Infantry Regiment (167e Régiment d'Infanterie de Forteresse (RIF)), Lt. Colonel Planet, command post at the Fort de Koenigsmacker

• Ouvrage Galgenberg, gros ouvrage A15 of six combat blocks and two entry blocks
• Ouvrage Sentzich, petit ouvrage A16 with a single combat block and no underground passages
• Ouvrage Métrich, gros ouvrage A17 of ten combat blocks and two entries
• Ouvrage Billig, gros ouvrage A18 of seven combat blocks and one entry

Peacetime barracks and support:

• Casernement de Cattenom
• Casernement d'Elzange[7]

During the early part of the Battle of France the SF Thionville was relatively quiet. Both sides kept up shelling and harassing attacks, but there were no major engagements in the sector in May and early June 1940. Elsewhere, the situation was deteriorating fast. To the west, the German 16th Army was advancing up the valley of the Meuse to Verdun, aiming for Metz and Nancy. In the center, the German 1st Army had broken through at the Sarre on 15 June. To the east, the Rhine was crossed on the same day. German armies were moving freely behind French lines with the goal of encircling France's field armies, capturing the cities of Alsace and Lorraine, and cutting off the fixed fortifications.[11]

By mid-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.[12] Although the interval troops were able to temporarily escape, by the 17th the Thionville sector had been enveloped by the Germans from the east and west. Retreat was impossible for the fortress troops.[13]

On 21 June 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. Apart from determined German shelling of Block 5 at Rochonvillers, there were no significant attacks on Thionville sector ouvrages.[13][14]

Following the armistice, brief negotiations undertaken by the commandant of Kobenbusch settled on a formal surrender for the garrisons west of the Moselle on 30 June. No such negotiations took place to the east until French officers received confirmation directly from General Huntziger that they were to surrender their fortifications. The eastern positions of the SF Thionville were surrendered on 2 July 1940[15]

While the main Maginot fortifications played no significant role in the Lorraine Campaign of 1944, the pre-Maginot fortifications of Thionville posed a significant obstacle to the advance of American forces, most notably the Fort de Koenigsmacker. The U.S. 90th Infantry Division captured Koenigsmacker after three days of hard fighting on 12 November 1944.[16][17]

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, Rochonvillers, Molvange, and Bréhain of the neighboring former SF Crusnes were designated the môle de Rochonvillers ("breakwater") in 1951 and were placed back into service after a period of rehabilitation. Petit ouvrage Immerhof was included in this assemblage[18] Lesser positions, such as Soetrich, Bois-Karre and Sentzich, were repaired and kept as government property, as were the remaining gros ouvrages in the sector, 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.[19]

In the early 1960s, three ouvrages were renovated as military command centers. Rochonvillers was converted for use as a wartime command center for the Central Army Group (CENTAG) of NATO and was used for this purpose from 1961 to 1967, when France withdrew from the NATO integrated command structure.[20][21] In a similar manner, Molvange became the wartime command center for the 4th Allied Tactical Air Forces, again from 1961 to 1967. The French military continued to make use of Molvange until 1999.[22][23] Soetrich saw a similar role in the 1960s.[22][24] Rochonvillers was reactivated in 1980 as the wartime command center for the French First Army, operating in that role until 1998.[25] In each the comparatively spacious underground barracks, magazine space and utility areas were used and expanded. The combat blocks were not used and were sealed from the occupied areas.

Fort de Guentrange, main caserne