The Casemate de Marckolsheim Sud is a pre-World War II fortified position near the Rhine river in eastern France.

As a unit of the Fortified Sector of Colmar, the casemate was part of French defenses during the German assault of 15–18 June 1940, Operation Kleiner Bär.

Marckolsheim Sud's numerical designator was 35/3, referring to its place in the third, or "village" line of fortifications, about 2 kilometres (1.2 mi) back from the river bank.

[1] Unlike other portions of the Maginot Line, the Rhine defenses were not interconnected, consisting of individual casemates or blockhouses a few hundred meters apart, arranged to fire along the length of the defended frontier.

[3] Marckolsheim Sud was restored in 1972[4] and houses a museum, the Musée Mémorial de la Ligne Maginot du Rhin.