The narrow canyon at Saint-Maurice facilitated both trade and defense. The bridge over the Rhone was built around the 12th century and was the first bridge upstream of Lake Geneva after the Roman bridge of Massongex (2 km downstream Saint-Maurice). The fortifications in the canyon was gradually expanded in 1831, 1848, 1859 and finally in 1892. During the Second World War, the fortifications at Saint-Maurice were one of the three main pillars of the National Redoubt. In 1995, the fortifications were abandoned and opened as a tourist attraction. Following the army reforms of Armee 95 and XXI, the former mountain infantry military base of Saint-Maurice-Lavey has served as a training camp for the military police.