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 that contributed to the end of the Avignon Papacy. == Causes == The causes of the war were 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.