Vauban pré carré

Timeline

1. 1673Picardy frontier · PicardyDuring the Franco-Dutch War, after inspecting Saint-Quentin and Guise, Vauban wrote to Louvois: the mingling of friendly and enemy fortresses forced France to 'maintain three and hold one', wasting manpower and dispersing forces. He urged the king to 'cut the frontier into a square meadow' by treaty or war, keeping only front-line points that could support one another; this metaphor became the source of the later double defense line's name.
2. 1678–1680Northeastern French frontier · FlandersThe Treaty of Nyjmegen let France consolidate newly acquired places such as Lille and Valenciennes. After becoming Director of Fortifications, Vauban arranged two lines of fortresses 'in order of battle': the front line facing the Spanish Netherlands, the second line in depth in Artois and Hainaut, reinforced with canals and marshes. The siting principle was to abandon isolated inland towns and concentrate funds on frontier hubs able to deliver flanking fire to one another.
3. 1681–1697Fortress belt from Dunkirk to Lille · FlandersThrough the 1680s Vauban continuously rebuilt the defenses of Dunkirk's harbor, the citadel of Lille and the towns of Artois, turning the two lines from a list into garrisonable, maneuverable belts of works. During the Nine Years' War coalition forces repeatedly struck the northern frontier; though not unbreakable, the line forced attackers to besiege town by town and slowed their penetration, proving the value of the 'square' as a national frontier strategy rather than a single bastion plan.