The French invasion and defeat and the exile of the Medici gave particular prominence within the new republican regime of Florence to a friar, Girolamo Savonarola. The son of a prominent physician, Savonarola had been born at Ferrara, entered the Dominican order at Bologna at the age of 23, and rapidly acquired fame as a theologian and preacher. In the years 1482–85 he served in the convent of San Marco at Florence; he returned there at the express wish of Lorenzo de’ Medici and became prior in 1491. In those years Savonarola preached conventional apocalyptic sermons warning of God’s punishments that awaited Florentine sinners, including, notably, those guilty of evil in government.

Following the passage of Charles VIII’s army, this message took on new forms. Drawing upon earlier Florentine mystical traditions, Savonarola now preached the doctrine that, in return for moral purification, Florence would soon become “the new Rome,” enjoying power, dominion, and success in this world. This flattering teaching, which was especially appealing after Florence’s humiliation, brought a wide circle of personal adherents (the Piagnoni, or “Wailers,” as their opponents called them), who enthusiastically backed Savonarola’s campaigns (not in themselves untypical of revivalist movements of the age) against gambling, blasphemy, and illicit sex. From 1497 Savonarola organized bands of young men to go from house to house to persuade their inhabitants to surrender those worldly possessions to which they were particularly attached, such as dice, books, paintings, and elegant dresses. Savonarola’s followers then placed these “vanities” on a bonfire and solemnly dedicated their destruction to the Lord.

In the controversy of 1495 as to what form of government should replace that of the Medici, Savonarola supported the party seeking the widest extension of popular participation. It is unlikely that Savonarola had any decisive influence on the political fortunes of the city; nonetheless, he came to be associated with the many failures of the government in those years and to be seen as an enemy by the parties of the Bigi (looking for the return of the Medici), the Arrabbiati (who hoped for a much more exclusive, less broadly based, republican government), and the Compagnacci (those who resented the puritanical way of life now imposed on the city). In particular, he attracted enemies through his unflinching support for an alliance with France, which isolated the commune in Italy but brought no response in loyalty from Charles VIII. His foreign-policy stance and his evangelical denunciation of the wickedness of the papacy aroused the hostility of Pope Alexander VI. In June 1497 the friar was excommunicated and commanded to remain silent. Defying this decree, Savonarola resumed preaching early in 1498 and included in his sermons appeals for a general council to reform the church. Such defiance, combined with a certain revulsion against the unrelenting moral crusade, led the secular government in April 1498 to turn against Savonarola. He was accused of heresy, tortured, and finally hanged and burned in the Piazza della Signoria (May 23).

Yet the contrast between the austerity of Savonarola’s life and the licentiousness of the Borgia pope who condemned him, as well as the destiny that the friar had prophesied for the Florentines, lingered in the minds of many, including some of the city’s most distinguished citizens, and in the last Florentine republic, of 1527–30, the memory of his exalted prophecies was still to sustain those who resisted the Medici and the emperor Charles V.