1210-1276. Pope from 1271. Born Teobaldo Visconti of Piacenza, he succeeded Clement IV (d.1268) after a vacancy of three years which ended when Bonaventura, Franciscan minister general, forced the cardinals into action. Canon of Lyons, then archdeacon of Liège, the future pope studied in Paris, then went to England in 1270 before setting out for the Holy Land. Unlike his predecessors, he concentrated less on secular concern than on spiritual revival and reunion. Interested in the affairs of the Latin East, the Kingdom of Jerusalem, he also established monarchical authority in Germany by inviting electors to designate a king of the Romans, persuading Alfonso of Castile to resign his claims. In 1273 at Lausanne he confirmed their election of Rudolph I of Hapsburg. He convoked the Second Council of Lyons to resume talks with the Greek Church, asking Michael VIII Palaeologus to send his ambassadors; agreement was reached, but the reunion was short-lived. A new crusade was discussed and financial preparations made, but nothing happened. Knowing the difficulty of his own election, Gregory had the council establish rules for papal election, for which he constitutionally created the conclave with Ubi periculum, 1274.