Fortified Sector of Montmédy

147th Fortress Infantry Regiment (147e Régiment d'Infanterie de Forteresse (RIF)), Colonel Pinard, with the 55th DI as interval troops

136th Fortress Infantry Regiment (136e Régiment d'Infanterie de Forteresse (RIF)), Lt. Colonel Vinson, with the 3rd DINA as interval troops

The Mouzon subsector was not considered part of the Maginot fortifications.[1] However, a gros ouvrage was originally proposed for the sub-sector, the Ouvrage de Vaux-les-Mouzon.[10]

155th Fortress Infantry Regiment (155e Régiment d'Infanterie de Forteresse (RIF)), Lt Colonel Culot, with the 3rd DIC as interval troops

• Ouvrage La Ferté, petit ouvrage of two combat blocks
• Ouvrage Chesnois, gros ouvrage of seven combat blocks
• Ouvrage Thonnelle, petit ouvrage of four combat blocks and two entry blocks
• Ouvrage Velosnes, gros ouvrage of six combat blocks

Peacetime barracks and support:

• Casernement de la Ferté (never built)
• Casernement de Montmédy[1]

132nd Fortress Infantry Regiment (132e Régiment d'Infanterie de Forteresse (RIF)), Lt. Colonel Blanchet, with the 41st DI as interval troops, command post at Grand-Failly. The Marville sector was a separate sector, the Defensive Sector of Marville, until March 1940.[11]

• Chiers Line: 11 blockhouses along the Chiers Valley (FCR/STG).
• Principal Line of Resistance: 10 blockhouses and one casemate (FCR/STG)
• Mangiennes-Pierrepont CEZF reinforcing line: four STG blockhouses[1]

On 13 May 1940, the German Army Group A attacked the French 2nd Army in the vicinity of Sedan and Monthermé. The attack came as a surprise to the French forces of the Sedan subsector. The French 55th Infantry Division, a second-line reserve formation, had spent most of its time constructing blockhouses along the line of the Meuse and Chiers rivers, with priority going to the Chiers line. When the German attack came, it found the 55th ID unprepared for combat, and its blockhouses along the Meuse, the focus of the German attack, were incomplete and unarmed. The attack by the German 1st, 2nd and 10th Panzer Divisions was preceded by a heavy aerial bombardment, which, while ineffective at causing casualties or damage to fortifications, effectively destroyed the division's will to resist. German infantry advances late on the 13th produced a disorganised retreat, and by the 14th the Germans had broken through the French defences.[12][13]

As the French forces in the Sedan subsector fled, the Chiers line in the Mouzon subsector was exposed. Ordered by General Huntziger to retreat to new positions farther south, the end of the Montmédy Bridgehead became exposed. This was composed of the village of Villy, occupied by the 3rd Colonial Infantry Division, backed up by Ouvrage La Ferté, the effective western end of the Maginot Line. The Germans immediately moved to attack La Ferté (known to the Germans as Panzerwerke 505) with the 71st Infantry Division. La Ferté, as part of the Maginot Line, was designed to be supported by its neighbours when under attack. Lacking a neighbour to the west, it had to depend on Ouvrage Chesnois for artillery support. However, the Maginot fortifications in the area were farther apart than in other sectors, and La Ferté was at the limit of Chesnois' artillery range. La Ferté was itself lightly armed, although it had been augmented with two artillery casemates armed with 75 mm guns. These casemates, however, were not connected as part of the position's integrated defences, lacking a secure underground connection to the main position.[9][12]

By 15 May the Germans were preparing an attack on Villy and La Ferté. On the 17th the Germans seized Hills 226 and 311, which commanded the ouvrage and were used as firing positions for artillery. The Villy artillery casemates were evacuated by the French the same day. On the 18th Villy village was occupied by the Germans, despite determined French resistance from a series of fortified houses in the village. La Ferté was encircled. On 18 May the Germans moved closer to the ouvrage, employing direct fire with four 88 mm guns. The exposed cloches and turrets became untenable, severely reducing the ouvrage's ability to resist the assault. A French counterattack failed. With the upper levels of both blocks on fire, resistance ceased on the 19th. Germans with respirators entered on the 20th and determined that the garrison was dead, killed by carbon monoxide poisoning.[9][12]

In June the remaining garrisons of the Tête de Pont de Montmédy were ordered to withdraw the night of 10–11 June to straighten French lines, and to avoid La Ferté's fate. The fortifications' arms and infrastructure were sabotaged before they were abandoned. Evacuation was complete by 12 June, a day ahead of the scheduled withdrawal, which resulted in the uncovering of the west flank of Ouvrage Ferme Chappy to the east.[12] The German 169th Infantry Division advanced to take possession of the salient on 13 June 1940.[14]

The Germans stripped the Montmédy fortifications during the Occupation, removing weapons for re-use and salvaging the massive steel cloches for scrap. While Maginot fortifications in other sectors were restored for further use during the Cold War, the SF Montmédy was not reactivated.[15]

The 132nd Fortress Infantry Regiment was shifted from the SF Crusnes to the SF Montmédy on 16 March 1940, holding the Chiers line. As part of a general withdrawal of French forces from the Maginot Line, the 132nd RIF pulled back on 13 June and joined the Division de marche Burtaire, retreating to Verdun. The regiment was assigned to hold the Fort Douaumont on 14 May. On the 15th the regiment was ordered to continue retreating in the direction of Toul. It was eventually captured to the south of Toul in the area of Colombey-les-Belles and Goviller between 20 and 22 June.[16]

The 136th Fortress Infantry Regiment covered the Mouzon subsector. The sector came under air attack from 10 May 1940, with infantry attack from 12 May. On the 14th the regiment moved back to the Inor belt of fortifications. On 21 May the 6th company was captured by German forces in the Hache Forest and the Inor line was abandoned, falling back to Stenay. As the unit fell back, it organised anti-tank barricades along the route. The 9th company was captured at Azannes on 14 June. The 136th was at Crepey on 25 June for the armistice.[17]

The 147th Fortress Infantry Regiment was stationed on the Sedan subsector. The regiment came under attack from 13 May and was pushed back to the Fort du Rozelier near Verdun by 21 May, when it was attached to the 71st Infantry Division, which became the 17trh ID two days later. Reorganised as the 59th Light Infantry Regiment on 5 June, the regiment fall back to Arc-en-Barrois.[18]

The 155th Fortress Infantry Regiment held the Tête du Pont de Montmédy, the most exposed portion of the sector, including La Ferté. The regiment was engaged from 13 May, and retreating to the Inor area after the loss of La Ferté and its garrison on 19 May. The units sabotaged their positions and retreated on 12 June. They were attached to the ;division de marche Burtaire, falling back to the Verdun and Saint-Mihiel area. After briefly freeing Gironville, the regiment was captured on 20–22 June near Toul.[19]