In 1628, Antonio was appointed Prefect of the Apostolic Signatura, in 1630 he was made the papal legate in Urbino and in 1633 he became legate in Avignon where he developed close contacts with various French church power brokers. During his time in France he became unwell and employed Joseph Barsalou as his "private physician". He returned to Rome and assumed the post of Camerlengo of the Holy Roman Church in 1638. In 1636, against the wish of his uncle the Pope, he accepted the post of Crown-Cardinal-Protector of the Kingdom of France. It has been estimated that during Urban's 21-year pontificate, Barberini amassed more than 63 million scudi in personal wealth.