It is difficult to define the exact mutual relations of Pope and city in any corner of Italy, but it is certain that Perugia found Papal power useful to her in many ways, and that on whatever side she happened to have a quarrel on hand, she always turned to the Papal See for help and arbitration. In spirit she was always Guelph, fighting under the emblem of the Guelph lion, and full of Guelph interests. Yet, although openly exercising self-government, almost in the manner of a free republic, under the protection and nominal rule of the popes, she was at the same time patronised by the emperors. In 1355 we read that her ancient privileges were confirmed and new ones granted by the Emperor Charles IV., who seems to have considered it worth his while to gain the friendship of her citizens.
Up to this period we have only had to deal with pleasant passing visits of the popes who sojourned in the city for a while. The time came, however, when the noose which Innocent had so lightly cast about their necks began to pull and tighten. The Perugians revolted hotly against the Popes of Avignon, who, incensed at their rebellion, attempted to check it by every means in their power. To understand the painful struggles which follow, it is necessary to remember that the end of the fourteenth and the whole of the fifteenth centuries were the most prosperous period in Perugia's history. She had grown steadily and uninterruptedly both in power and riches, and in spite of terrible obstacles, ever since the day when the Romans rebuilt her walls more than fifteen hundred years before. In these two centuries she erected her public buildings, extended and settled her government, coined money, started her university, settled with her habitual promptitude all suspicion of rebellion, became one of the _Tre Communi_ of Florence, Siena and Perugia, and whilst achieving all these things she continued to foster the passionate feuds and hopeless enmities between the different factions which we have described above. Having grown strong and prosperous it was natural that she should resent any open attempt of a foreign power to subject her, and such an attempt came in the middle of the fourteenth century from the Papal See.