Le Perthus became French territory after the Treaty of the Pyrenees (1659). Bellegarde was captured by the Spaniards in 1674, but retaken by Schomberg in 1675. In 1678, Vauban's plans for the new fortress of Bellegarde were approved. During the War of the Pyrenees, the fortress was besieged in May - June 1793 by the Spanish and then by the French (May - Sept. 1794). During World War II, the fort was used as a holding prison by the Gestapo for escaped prisoners of war and enemy agents.