Jean was godfather to Charles the Bold in 1433 and to the Dauphin in 1459. In 1435 he played an important part in the formation of the Congress of Arras. He was subsequently charged with bringing the city of Amiens under Burgundian control. In 1436, Jean commanded the Burgundian-Flemish army that besieged Calais and was blamed for the complete failure of the expedition. During the Revolt of Ghent (1449–1453), he lifted the siege of Oudenaarde and in 1453, he defeated William I of Brunswick-Wolfenbüttel at Thionville, securing the Duchy of Luxembourg for Burgundy.