Casemate de Marckolsheim Sud, Military museum in Marckolsheim, France.

The Casemate de Marckolsheim Sud is a double casemate of the Maginot Line's Rhine defenses, built in the mid-1930s by CORF. Its concrete face bears the inscriptions "MEMORIAL DE LA LIGNE MAGINOT DURHIN" and "CASEMATE 35-3". The position has two lateral firing embrasures for twin Reibel machine guns and 47mm anti-tank guns, plus two cloches on top: a central JM cloche and a GFM cloche to one side.

Built in the mid-1930s by CORF as position 35/3 in the third, or village, line about 2 km from the Rhine, Marckolsheim Sud was commanded in 1940 by Lieutenant Marois of the 42nd Fortress Infantry Regiment. On 15–17 June 1940 German troops of the 360th Infantry Regiment, 221st Infantry Division, attacked; 8.8 cm guns disabled one cloche and Stuka bombs buried the other. Assault teams threw explosives into the openings, killing Corporal Louis Gardet, and the garrison surrendered on the 17th. Restored in 1972, it now houses the Musée Mémorial de la Ligne Maginot du Rhin.

The site shows how France aimed to defend its Rhine border and what techniques were used for protection. Visitors can see how this defensive line reflected the military thinking of that era.

Access to this underground facility requires caution and careful movement through narrow passages. It is advisable to wear comfortable shoes and allow time to explore the different chambers.

Three 88 mm shells fired at the observation cloche in June 1940 are still lodged in the steel and can be seen today. The casemate was built in the mid-1930s, not to 1940 specifications, and its two cloches made it larger than most in the sector.