of the House of Savoy, pursued a particularly ruthless policy against the league to re-establish control over these cities. He convinced Pope Gregory to hire Breton mercenaries. To quell an uprising of the inhabitants of Cesena he hired John Hawkwood and had the majority of the people massacred (between 2,500 and 3,500 people were reported dead). Following such events opposition against the papacy strengthened. 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. The entire city of Florence was excommunicated and as reply the forwarding of clerical taxes was stopped. Trade was seriously hampered and both sides had to find a solution. In his decision about returning to Rome, the Pope was also under the influence of Catherine of Siena, later canonized, who preached for a return to Rome. This resolution was short-lived when, having returned the papal court to Rome, Pope Gregory XI died. A conclave met and elected an Italian pope, Urban VI. Pope Urban alienated the French cardinals, who held a second conclave electing one of their own, Robert of Geneva, who took the name Clement VII, to succeed Gregory XI, thus beginning a second line of Avignon popes. Clement VII and his successors are not regarded as legitimate, and are referred to as antipopes by the Catholic Church. This situation, known as the Western Schism, persisted from 1378 until the ecumenical Council of Constance (1414–1418) settled the question of papal succession and declared the French conclave of 1378 to be invalid. A new Pope, Pope Martin V, was elected in 1417; other claimants to succeed to Avignon line (though not resident at Avignon) continued until c. 1437. Legacy The period has been called the "Babylonian captivity" of the popes. When and where this term originated is uncertain although it may have sprung from Petrarch, who in a letter to a friend (1340–1353) written during his stay at Avignon, described Avignon of that time as the "Babylon of the west", referring to the worldly practices of the church hierarchy. The nickname is polemical, in referring to the claim by critics that the prosperity of the church at that time was accompanied by a profound compromise of the papacy's spiritual integrity, especially in the alleged subordination of the powers of the Church to the ambitions of