254th Pope of the Catholic Church. Pontificate 1831 - 1846. Member of the Camaldolese Order. The last non-bishop to be elected. Strongly conservative and traditionalist, he opposed democratic and modernising reforms in the Papal States and throughout Europe, seeing them as fronts for revolutionary leftism, and sought to strengthen the religious and political authority of the papacy. In 1839, Pope Gregory XVI wrote In Supremo Apostolatus, an historic Papal Bull condemning the international slave trade.