From 1874–1880, General Raymond Adolphe Séré de Rivières oversaw the construction of the Séré de Rivières system, a line of fortresses long from Belfort to Épinal and another line of similar length from Toul to Verdun, about back from the frontier. The River Meuse flows northwards from Toul to Verdun, Mézières and Givet on the Belgian border and a tributary of the Moselle between Belfort and Épinal, near parallel to the 1871–1919 French-German border. The (Charmes Gap), wide, between Épinal and Toul was left unfortified and the fortress city of Nancy was to the east, from the German frontier. A second series of fortifications, to prevent the main line being outflanked, was built in the south, from Langres to Dijon and in the north from La Fère to Rheims and from Valenciennes to Maubeuge, although for financial reasons these defences were incomplete in 1914.