Fortified Sector of Altkirch

The Fortified Sector of Altkirch (Secteur Fortifiée d'Altkirch) was the French military organization that in 1940 controlled the section of the French frontier with Germany and Switzerland in the vicinity of Basel. The sector's principal defense against an advance from Germany was the Rhine itself, which could be crossed only by boat or by seizing a bridge crossing. The frontier with Switzerland was not regarded as a high-risk location, save for a possible advance by German forces through Switzerland. Originally planned as a full extension of the Maginot Line with artillery ouvrages, the sector's fortifications were scaled back and chiefly took the form of casemates and blockhouses. The SF Altkirch adjoined the Fortified Sector of Mulhouse to the north and the Fortified Sector of Montbéliard to the west.

The region bordering Switzerland was treated as a low-priority area, but received a substantial number of casemates and blockhouses nonetheless. Initial plans floated in 1934 proposed four artillery ouvrages at Stetten, Ranspach-le-Haut, Bettlach and Trois-Maisons, with four more infantry ouvrages at Uffheim, Helfrantzkirch, Ranspach-le-Haut, Bettlach and Oltingue. These were to be supported by 68 casemates. The project was cancelled in 1936 and were replaced by a more modest program that created three centers of resistance at Sierentz, Bettlach-Oltingue and at Roedersdorff-Blochmont. A total of six blockhouses were built, each housing two 75mm guns, with six more blockhouses armed with two 47mm guns, two machine guns and two automatic rifles.

Three more resistance centers were proposed at Stetten, Ransbach-le-Haut and Trois-Maisons in 1937, but were replaced by more casemates, prepared for mobile 155mm and 240mm howitzers to cover the bridges at Basel and Huningue. Thirteen blockhouses, four observation positions and fourteen infantry shelters were planned for the Glaserberg, along the Swiss border.

Until 16 March 1940, the Altkirch sector was part of the Fortified Region of Belfort. Afterwards, the Altkirch sector was under the command of the 44th Army Fortress Corps under General Tence, which was in turn under the command of the French 8th Army, General Garchery at the Fort de Giromagny, part of Army Group 3 under General Besson. The 44th Corps' headquarters was at Dannemarie. The 67th Infantry Division, commanded by General Boutignon, provided infantry support. The 67th DI was a series B reserve division, not suitable for heavy or sustained combat Following to its reorganization, the sector was called the Defensive Sector of Altkirch.

...
Wikipedia