Breisach (brĪˈzäkh) [key], town (1994 pop. 11,680), Baden-Württemberg, SW Germany, on the Rhine River. Its manufactures include wine, agricultural produce, textiles, electrical goods, and paper. An old town, it has long been coveted because of its strategic location. It was fortified by the Romans, who called it Mons Brisiacus. It became an imperial town in 1275. Bernhard of Saxe-Weimar took the town in 1638. Louis XIV secured it for France in the Peace of Westphalia (1648) and ceded it back to the emperor in the Treaty of Ryswick (1697), but built a new fort, Neuf-Brisach (Ger. Neu Breisach ), on the opposite side of the Rhine. The French repeatedly captured Breisach during the 18th cent. but gave it to Baden in 1805.