 The pestilence of 1630–1631 killed 70% of Modena's inhabitants.After the outbreak of the Thirty Years' War he sided with Spain and invaded the duchy of Parma, but upon visiting to Spain to claim his reward, he could only acquire Correggio by a payment of 230,000 florins.Later followed the First War of Castro, in which Francesco's Modena joined Venice and Florence and sided with the Dukes of Parma against Barberini Pope Urban VIII, aiming to reconquer Ferrara.