War of the Eight Saints The War of the Eight Saints ( 1375 – 1378 ) was a war between Pope Gregory XI and a coalition of Italian city - states led by Florence , which contributed to the end of the Avignon Papacy . Causes . The causes of the war are rooted in interrelated issues : Florentine opposition to the expansion of the Papal States in central Italy ( which the Avignon Popes had set as a condition for their return ) and antipathy toward the " Parte Guelfa " in Florence . Specifically , Florence feared in the autumn of 1372 that Gregory XI intended to reoccupy a strip of territory near Lunigiana , which Florence had conquered from Bernabò Visconti , and that the Ubaldini might switch from Florentine to Papal allegiance . Gregory XI also harbored various grievances against Florence for their refusal to directly aid him in his war against the Visconti of Milan . When Gregory XI ' s war against Milan ended in 1375 , many Florentines feared that the pope would turn his military attention toward Tuscany ; thus , Florence paid off Gregory XI ' s main military commander , English " condottiere " John Hawkwood , with 130 , 000 florins , extracted from local clergy , bishops , abbots , monasteries , and ecclesiastical institutions , by an eight - member committee appointed by the Signoria of Florence , the " otto dei preti " . Hawkwood also received a 600 florin annual salary for the next five years and a lifetime annual pension of 1 , 200 florins . The transalpine mercenaries employed by Gregory XI against Milan , now unemployed , were often a source of friction and conflict in papal towns . The War . Florence formed an alliance with Milan in July 1375 , immediately prior to the outbreak of the war , and the prosecution of the war was entirely delegated to an eight - member committee appointed by the Signoria of Florence : the " otto della guerra " . Florence incited a revolt in the Papal States in 1375 . Florentine agents were sent to more than forty cities in the papal states — including Bologna , Perugia , Orvieto , and Viterbo — to foment rebellion , many of which had only been re - submitted to papal authority by the efforts of Cardinal Gil Álvarez Carrillo de Albornoz . Humanist Chancellor of Florence Coluccio Salutati disseminated public letters urging the cities to rebel against the " tyrannical " and " corrupt " papal rule , instead urging a return to " all ' antica " Republicanism . Pope Gregory XI excommunicated all members of the government of Florence and placed the city under interdict on March 31 , 1376 , banning religious services in Florence and legalizing the arrest and enslavement of Florentines and the confiscation of their property throughout Europe . Initially , rather than attempting to disobey the interdict , Florentines organized extra - ecclesiastical processions ( including flagellants ) and confraternities , including the re - emergence of groups such as the Fraticelli , who had previously been deemed heretical . The edifice of the Florentine inquisition was destroyed , and the Signoria rolled back legal restrictions on usury and other practices frowned on by the ( now defunct ) ecclesiastical courts . However , on October 1377 , the government of Florence forced the clergy to resume religious services causing Angelo Ricasoli , Bishop of Florence , and Neri Corsini , Bishop of Fiesole , to flee Florentine territory . The heavy fines and confiscations issued by the Signoria on prelates who left their posts , the " most extensive liquidation of an ecclesiastical patrimony attempted anywhere in Europe before the Reformation , " may have been motivated to pay for the increasingly expensive conflict . The total cost of the war for Florence would reach approximately 2 . 5 million florins . As a result of Gregory XI ' s economic sanctions , merchants of the Florentine " diaspora " were hurt economically throughout Europe , particularly the Alberti bankers in Avignon , although the interdict was ignored by many , including Charles V of France . Hawkwood honored his agreement with the Florentines not to make war in Tuscany , limiting himself to putting down the various rebellions within the papal states ; in 1377 Hawkwood abandoned Gregory XI entirely and joined the anti - papal coalition . Gregory XI ' s other " condottieri " also limited their acitivities to Romagna , notably sacking Cesena in February 1377 . In the spring of 1377 , papal mercenaries recaptured Bologna , which up until that point had been a key Florentine ally . In 1377 , Cardinal Robert of Geneva ( future Avignon Pope Clement VII ) led the army of Gregory XI in an attempt to quell the revolt , and Gregory XI himself returned to Italy to secure his Roman possessions , " de facto " ending the Avignon Papacy . Gregory XI arrived in Rome in January 1378 , after a difficult journey ( including shipwreck ) , and died there in March 1378 . Resolution . The war ended with a peace treaty concluded at Tivoli in July 1378 , negotiated with Pope Urban VI following the death of Gregory XI and with the beginning of the Western Schism . Under the treaty , Florence was to pay the Pope 200 , 000 florins ( as opposed to Pope Gregory XI ' s original indemnity requirement of 1 , 000 , 000 florins ) , repeal all laws placed against the Church by the secular government , and restore all property confiscated or looted from the clergy . The Pope , in return , was to repeal the interdict placed on Florence and mend the ecclesiastical community ' s diminished favor of Florence . The Eight Saints . The Eight Saints ( ) may refer to one or both of two , eight - member " balía " appointed by the Signoria of Florence during the war . When Florence arranged a nonaggression pact with Hawkwood at a cost of 130 , 000 florins , a special commission of eight citizens was created to levy a one - year , forced loan on the clergy of Florence and Fiesole to cover the sum . A second council of eight men was later created to make the military and diplomatic arrangements necessary to carry on a war against the Pope . The group identity of the Eight Saints remains a controversial subject . The levy committee is most widely accepted as the " otto di santi " by scholars , though some argue that " otto di santi " refers to the war council . The first historical reference to the Eight of War ( ) as the " otto santi " occurs in 1445 with the account of Florentine historian Domenico Buoninsegni ; it does not appear in the accounts of contemporaries of the war such as Leonardo Bruni and Giovanni Morelli . Buoninsegni had applied the appellation — used in August 1378 to refer to an eight - member group ( " Gli Otto Santi del Popolo di Dio " ) formed by the Ciompi revolt , which ensued immediately after the War of the Eight Saints — to the " otto della guerra " . In contrast , the moniker is used in the March 31 , 1376 bull of excommunication to refer to the " otto dei preti " ( the levy committee , literally meaning " eight priests " ) . The " otto dei preti " , appointed July 7 , 1375 to carry out the taxation of the clergy for the nonaggression pact included : The " otto della guerra " ( war council ) were appointed August 14 , 1376 and consisted of four guild representatives and four members of the nobility . " Major Guild Representatives " " Minor Guild Representatives " " Members of Elite Florentine Families "