The conflict between the pope and the Holy Roman Emperor was fundamentally a dispute over which of them was the leader of Christendom in secular matters. This state of affairs culminated in the unbridled declaration of papal supremacy, Unam sanctamin November So, for a time, there were three claimants to the papacy: one in Rome, one in Avignon, and one in Pisa.
Frederick II ignored this and was rather successful in the Holy Land. The latter was directly challenged by Philippe IV when he demanded a posthumous trial of his former adversary, the late Boniface VIII, for alleged heresy.
The man elected to succeed him, Urban VI, was so hostile to the cardinals that 13 of them met to choose another pope, who, far from replacing Urban, could only stand in opposition to him. Florence came in open conflict with the Pope, a conflict called "the war of the eight saints" in reference to the eight Florentine councilors who were chosen to orchestrate the conflict.
Overall the public life of leading church members resembled more those of princes, rather than members of the clergy.