The Visconti family's seizing of territory, in particular, was seen as a major threat to the Papacy. Members of the merchant family often took spiritual authority into their own hands and regulated temporal affairs throughout their land. As this served to further centralize the Visconti power and drew authority away from the papacy, battles between the two factions occurred frequently. Both groups would form alliances with local and international powers in order to suppress their rival's army and to prevent their opponent's accumulation of power. Galeazzo II was drawn into warfare with Pope Gregory XI when serving an alliance with his brother, Bernabò V; the papacy became his biggest military opponent during his reign of northern Italian city-states. The rivalry between Bernabò and Pope Gregory XI had been carried down from Pope Urban V, who sought to expel the brothers and to revoke their territorial possessions. Galeazzo stood to lose Angevin cities in Piedmont after pope Gregory attempted to suppress his army by forming alliances with local and international powers such as Genoa, Amedeo of Savoy, the Marquis of Monferrato, Niccolo D’Este, Albert, Duke of Austria, Gerald, the elector of Nuremberg and Charles, the Holy Roman Empire. By doing so, Gregory XI looked to gain territory regionally and to deprive the Visconti brothers from international mercenary support. The battle between the papacy and the Visconti brothers continued until Gregory signed a peace treaty with the brothers in the spring of 1378.