The Casemate de Marckolsheim Sud is a pre-World War II fortified position near the Rhine river in eastern France. The casemate was part of an extension of the Maginot Line fortifications along France's border with Germany. 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. It has been preserved and is part of a museum focusing on the Rhine section of the Maginot Line. The museum is located at the eastern edge of the town of Marckolsheim.