 Complete the following phrase:  With the election of Walther von Supersax of Conches as bishop in 1457, the German-speaking part of the valley finally won the supremacy. At the outbreak of the Burgundian War in 1475 the bishop of Sion and the Zenden made a treaty with Bern. In November of the same year they seized all Lower or Savoyard Valais up to Martigny. In March 1476, after the victory of 