The War of the Eight Saints (1375-1378) pitted the Florentine commune against the papacy and produced political, economic, and spiritual consequences. Struck by excommunication and interdict, the Florentines responded by acting harshly toward the ecclesiastical institutions within their dominions: first through heavy fiscal impositions, and subsequently through the expropriation of extensive urban and rural properties. This article examines the effects of the fiscal and expropriative policies implemented during the conflict on the property holdings of ecclesiastical institutions. It takes as its privileged case study the Cistercian abbey of Settimo, located in the Florentine countryside. A particularly detailed accounting register makes it possible to reconstruct the economic situation of the monastery and to assess, with a good degree of reliability, the impact of these policies.