Pope, a title first given to all bishops of the Christian church, but now exclusively applied to the bishop of Rome or head of the Roman Catholic church. Tradition, confirmed by the faith of the church, represents St. Peter as the first bishop of Rome. Whether he were such or not, it was natural that the early bishops residing in the imperial city should acquire a large measure of influence and importance and that after the empire became Christian they should attain considerable temporal power. The temporal power was not fully established, however, until 754, under Pepin, king of the Franks. From that time the history of the papacy has been a contest of greater or lesser intensity with the princes and rulers of Europe, in which now one and now the other of the contending parties prevailed. At present the pope is stripped of all temporal power, but his authority over the church in all matters spiritual and ecclesiastical is supreme and unquestioned, the Vatican Council which assembled at Rome in 1870 having proclaimed his infallibility on all questions of faith and morals. Whenever a vacancy occurs in the papal chair, it is filled by the cardinals choosing one of their number to occupy the place. A history of the more important popes will be found under their several titles.