The Fort d'Illange is a fortification located to the south of Thionville in the Moselle department of France. It was built by Germany next to the town of Illange in the early 20th century after the annexation of the Moselle following the Franco-Prussian War. The Fort d'Illange was part of the Moselstellung, a group of eleven fortresses surrounding Thionville and Metz to guard against the possibility of a French attack aimed at regaining Alsace and Lorraine, with construction taking place between 1905 and 1911. The fortification system incorporated new principals of defensive construction to deal with advances in artillery. Later forts, such as Illange, embodied innovative design concepts such as dispersal and concealment. These later forts were designed to support offensive operations, as