After the defeat of 1870, Germany annexed the two districts of Alsace (except Belfort), the major part of Moselle and a part of Meurthe and Vosges, and prevented France from any attempt to reconquer this territory. The engineers of the Empire developed in Alsace and in Lorraine all the techniques coming from the art of fortifying in Germany: from Alexis von Biehler's forts in Strasbourg to the strongholds on the square of Metz. During 45 years, Germany built on its frontiers with France a coherent defensive system, consistent with its strategy and adapted to the army's operational plans proposed by Von Schlieffen:"the Empire's occidental shield". This fortified system has not been fully tested during the Great War, which has helped to create this idea of an undefeated, mighty and modern system.
Fortifications Allemandes D'Alsace Lorraine 1870-1918