​​Batterie Oldenburg, designated Stützpunkt 18, was established by German forces in 1940 in the dunes of the Moulin Rouge area, around 400 metres from the coastline northeast of Calais. Initially composed of two open circular gun emplacements connected by a Decauville railway to ammunition storage facilities, the site developed into a key coastal artillery position.

​In October 1940, construction entered a second phase with the addition of reinforced concrete Sonderkonstruktion casemates. These fortifications housed living quarters, technical rooms for ventilation and power generation, water reserves, and sanitary facilities. Two primary bunkers were constructed, named “Turm West Osel” and “Turm Ost Borkum.” Both were two-level structures; “Turm Ost” required over 16,000 cubic metres of concrete and included an extension. The work was carried out by a multinational labour force of roughly 600 French and Belgian engineers, technicians, and workers.

​Each casemate was armed with a 24 cm Schiffskanone KL/50 naval gun, with a range of 28.3 kilometres, shielded by frontal armour. The battery was also supported by early warning and fire coordination equipment, including a Seetakt radar and a rangefinder mounted on a wooden observation tower.

​By 1943, Batterie Oldenburg expanded with the addition of various shelters and gun positions, including two 7.62 cm Soviet guns under H629 bunkers, a 7.5 cm gun casemate (H612), and other positions for anti-tank and anti-aircraft defence. A fire control tower was begun but never completed, serving instead as a shelter.

​The battery’s defences included French 7.5 cm M33 guns, 4 cm Bofors, and 2 cm Oerlikon anti-aircraft weapons. In 1944, steel mesh screens were installed over the casemate openings to protect crews from shrapnel.

​On 1 October 1944, during the liberation of Calais, the second casemate was destroyed by an internal explosion in the ammunition stores as Canadian troops from the 3rd Infantry Division captured the site. At that time, the battery was commanded by Korvettenkapitän Hans Stührenberg, supported by three officers, 34 non-commissioned officers, and 138 sailors.