A set of fortifications of medieval origin, the fortified place of Verdun was completely modernized after the Franco-Prussian war of 1870, between 1874 and 1914.
It consisted of two powerful belts of armed forts and shelters surrounding the city and the underground citadel. Thus, it became one of the principal places of the defense system supposed to protect the French territory from an invasion.
According to the propaganda of the time, Fort Douaumont was the most powerful fortress of this type. However, it was conquered by the Germans in February 1916, at the beginning of the Battle of Verdun.
The German troops occupied it for eight months and used it as a base for their offensives.
Despite several attempts to reconquer the fort, the French did not take it back until October 24, 1916.