Clement VII (1342–94), one of the so-called antipopes. In 1309 Pope Clement V moved the seat of the papacy from Rome to Avignon, France, where it was subject to French control. In 1378 Pope Gregory XI returned the papacy to Rome, but died soon after the move. Urban VI was elected his successor, but he alienated the cardinals, who elected Robert of Geneva (Clement VII) pope in his stead. Clement acted as pope in Avignon, while Urban VI was pope in Rome. This period is known in Catholic history as the Great Schism. For 40 years (1378–1418) there were 2 rival lines of popes, until the Council of Constance settled the matter in favor of Rome. Since then, the Church has regarded the line of Avignon popes begun with Clement VII as illegitimate.