Ouvrage Einseling, Military fort in Longeville-lès-Saint-Avold, France

Ouvrage Einseling is a concrete fortification with armored gun turrets located on the Finselingerberg hill. The installation features underground passages, machine gun positions, and interconnected defense chambers built into the hillside structure.

Approved by the CORF in April 1932 and completed in 1933 by the contractor Borie of Paris for 7 million francs, Einseling was planned in two phases; the second, with an 81 mm mortar turret and a separate entrance block, was never built. On 21 June 1940 the German 167th Infantry Division attacked, but fire from Laudrefang's 81 mm mortars broke up the assault. The ouvrage surrendered on 25 June 1940, after the armistice, and was not renovated after the war.

The fort was part of France's border defense network and reflects the military engineering philosophy of the 1930s. Visitors can observe how the structure was designed to control the surrounding territory through its strategic placement on the hillside.

The fort is typically open to visitors only during special heritage days or by advance arrangement. Visitors should check locally for current access conditions and timing before planning a visit.

The fort's name came about through a spelling mistake during its construction, when the original designation was changed from Finseling to Einseling. This error was later formalized and remains the official name of the installation today.