On September 2, 1444, the cathedral chapter of Coutances Cathedral elected him Bishop of Coutances. In 1447, he was named papal legate to the Kingdom of England. He was transferred to the see of Pavia on October 3, 1453. He served as the papal legate of Pope Nicholas V and Pope Callixtus III to Germany, in which capacity he was present at the Diet of Regensburg of April 1454 and the Diet of Frankfurt of October 1454. At these two diets, his main goal was to promote war with the Ottoman Empire, which had recently captured Constantinople, the capital of the Byzantine Empire. On September 8, 1455, he was present in St Mark's Basilica in Venice for the ceremony of the departure of the Crusade. In 1456, he served as legate to Frederick III, Holy Roman Emperor.