GREGORY X, POPE. - Tedaldo Visconti, born in Piacenza ca. 1210; he became a canon and professor in his native city; taken into the service of Cardinal Pecorara, a famous diplomat of the time, he gained experience and made connections; he resided in Paris while St. Thomas Aquinas and St. Bonaventure were teaching there, was appointed archdeacon of the diocese of Liège, and papal legate in England. He traveled to the East with an expedition that failed due to the death of Louis IX. At the death of Clement IV, the Sacred College, gathered in Conclave at Viterbo, was divided by bitter dissensions and, failing to reach any conclusion, ended by appointing a commission with the power to decide, and, perhaps on the advice of St. Bonaventure, Tedaldo was chosen—who was neither a cardinal nor a priest and was still in the Holy Land (19 Sept. 1271). Upon his return he was crowned (23 March 1272) and assumed the name of Gregory X.
Gregory X carried out notable activity with the aim of pacifying minds and nations: he traveled personally to many Italian cities to reconcile the Guelph and Ghibelline factions, but with little success; he compelled the imperial electors to choose a titular head to end the great interregnum (succeeding, at the Pope’s suggestion, the modest feudal lord Rudolph of Habsburg, and this move was also intended to counterbalance French and Angevin encroachment); he was tolerant toward the Jews, took a great interest in Marco Polo’s journey to the East, received benevolently the ambassadors of Tartar and Mongol princes, established the Apostolic Almonry, and laid down new rules for the Conclave.
In 1274 he celebrated the Council of Lyon (v.), at which he achieved union with the Greek Church, though it proved short-lived. On his return journey from Lyon to Rome, Gregory X met Rudolph of Habsburg at Lausanne and reached an agreement with him regarding the coronation and an expedition to the East, but before reaching his see he died at Arezzo on 10 January 1276; he was buried in the cathedral, and in the 18th century he was accorded the title of blessed. The program of his pontificate reveals great zeal and uncommon political ability.