Including himself in the dynamics of post-medieval developments in the art of fortification, Vauban (1633-1707), wishing to reduce human losses, revolutionized the arts of poliorcetics and fortification. Three fortification systems can be deduced from the works carried out by Vauban. However, he seeks above all to adapt to the terrain13.
The conquest of Franche-Comté and the Holy Roman Empire by the Dutch War in 1674 made the fortification of the Belfort region, giving access to the Alsace plain, essential. According to the double barrier system of the Vauban square, Belfort is in second line behind Huningue and Neuf-Brisach. Belfort, a simple fortification still medieval in essence, then acquired the status of a royal fortress.
The Belfort fortification project proposed in 1687, following the formation of the Augsburg League, according to its second theoretical system. This system is based on the separation of the distant and close firing zones into two concentric enclosures. The outer enclosure is made up of detached fortified bastions overlooking the terrain. The interior enclosure is dedicated to close combat. This interior enclosure is formed by towers 27, 41 and 4614.
Vauban adapts the terrain by moving the Savoureuse River and adapts to the terrain by advancing a protective structure facing the Miotte - this is the Horn of Espérance -, and another on the glacis of the castle.