Grandnephew of Pope Honorius III, he studied at Paris and was made cardinal in 1261 by Pope Urban IV. Although old and crippled, he was elected on April 2, 1285, to succeed Pope Martin IV. His pontificate favoured the mendicant orders (i.e., religious orders avowing poverty and mobility) and promoted the study of Oriental languages at the University of Paris to aid those working toward a reunion of Western and Eastern churches. In his striving to restore Sicily to papal vassalage, he clashed with King Peter III of Aragon, who supported Sicilian independence.