Battle of Verdun - Verdun Sector in 1914

Verdun Sector in 1914

In 1914, following the German invasion of France, the First Battle of the Marne (5–12 September) and the capture of Saint-Mihiel (on 24 September) created a salient around Verdun. Although some forts underwent artillery bombardment by Big Bertha, the fortifications were not threatened with capture.

The heart of the city of Verdun was a citadel built by Vauban in the 17th century. By the end of the 19th century, a large underground complex had also been built which served as quarters for the troops inside the city. About 8 km (5.0 mi) beyond the walls of the city of Verdun was an outer double circular ring of 18 large underground forts (not including 12 smaller forts or redoubts), many of them featuring retractable/rotating artillery turrets equipped with short 75 mm (2.95 in) and short 155 mm (6.1 in) fortress cannons. This ring of 18 large underground forts protecting Verdun had been built at great cost beginning in the 1880s and according to the specifications of the Séré de Rivières system. The Verdun forts were variable in quality and size, and thus provided unequal potential to resist heavy artillery shelling.

The forts situated to the north and east of Verdun (e.g. Fort Douaumont, Fort Vaux, Moulainville) had been thoroughly hardened during the early 1900s with very thick steel-reinforced concrete tops resting on a sand cushion. Those hardened forts had also been equipped with regular 75 mm (2.95 in) field guns installed in reinforced concrete bunkers ("Casemates de Bourges") looking sideways, thus providing flanking fire across the intervals between the forts. However, several large forts built during the 1880s on the same defensive ring, but to the west and south of Verdun (e.g. La Chaume, Regret, Belrupt-en-Verdunois), had never been improved.