The Pazzi Conspiracy

What was the Pazzi Conspiracy?
The Pazzi Conspiracy was a plot to overthrow Medici rule in Florence by assassinating Lorenzo de' Medici and his brother Giuliano during High Mass in Florence Cathedral on 26 April 1478. The conspiracy drew together the rival Pazzi banking family, Pope Sixtus IV and members of his own household, and disaffected figures within Florence itself. It stands as one of the most dramatic episodes of Renaissance political violence, a plot to kill Florence's rulers at the altar of its own cathedral.

Why did the Pazzi family turn against the Medici?
The Pazzi were a wealthy banking family whose influence had long been overshadowed by the Medici, who dominated Florentine politics without ever holding formal hereditary power. Tension deepened when Pope Sixtus IV wanted funds to purchase the town of Imola for his nephew, and the Medici bank refused the loan on political grounds, only for the Pazzi bank to provide it instead. This decision won the Pazzi valuable papal favour and cost the Medici bank its position as the papacy's chief financial agent, deepening the rivalry between the two families considerably.

Who was involved in planning it?
Francesco de' Pazzi took the leading role among the conspirators, working alongside Archbishop Francesco Salviati, whom Lorenzo had blocked from taking up his appointed see in Pisa, and Girolamo Riario, the pope's ambitious nephew and Count of Imola. Pope Sixtus IV appears to have known of and approved a plan against Medici power, though he later insisted he had never sanctioned murder itself. The head of the Pazzi family, Jacopo de' Pazzi, joined only reluctantly, apparently persuaded that the plot could not now be stopped.

How was the plot carried out?
The conspirators originally hired the mercenary captain Giovanni Battista da Montesecco to kill Lorenzo, but he refused when he learned the murder was to take place inside a church during Mass, regarding the setting as an act of sacrilege he could not commit. Two priests were recruited to kill Lorenzo in his place, while Francesco de' Pazzi and Bernardo Bandini dei Baroncelli took responsibility for Giuliano. The signal for the attack was to be the moment the priest raised the host during the consecration of the Eucharist.

What happened to Giuliano de' Medici?
Giuliano de' Medici was stabbed to death within the cathedral, struck by Francesco de' Pazzi and Bandini with a ferocity that left him with nineteen separate wounds. Francesco reportedly attacked with such violence that he wounded his own leg in the process, a detail later chroniclers seized upon as a symbol of the conspiracy's chaotic execution. Giuliano's death was instant and total, achieving the one unambiguous success the conspirators managed that day.

How did Lorenzo survive?
The priests assigned to kill Lorenzo proved far less committed than Giuliano's attackers, and Lorenzo suffered only a wound to the neck before fighting his way clear of the assault. He fled into the sacristy, where loyal supporters barred the heavy bronze doors against the confusion outside until the immediate danger had passed. His survival transformed the conspiracy's outcome entirely, since a Florence that still had Lorenzo alive to lead it responded with fury rather than collapsing into the political vacuum the plotters had hoped for.

How did Florence respond to the attack?
News of the attack spread through Florence within hours, and the city's population rallied overwhelmingly behind the surviving Medici rather than the conspirators, who had hoped for a popular uprising against Medici dominance. Crowds hunted down suspected participants in the streets, and the government moved immediately to secure the city and identify everyone connected to the plot. The conspiracy's failure to win public support in its opening hours effectively decided its fate before the day was over.

What happened to the conspirators?
Retribution was swift and brutal. Archbishop Salviati and Francesco de' Pazzi were hanged from the windows of the Palazzo della Signoria within hours of the attack. Jacopo de' Pazzi fled the city but was recognised and captured within the Apennines a few days later, brought back to Florence, and hanged in turn from the same building. Dozens of others connected to the plot were killed in the following days, and the Pazzi name itself was formally proscribed, its coat of arms destroyed and its surviving members barred from public office and even from marrying under the family name.

What was the political aftermath?
Pope Sixtus IV, enraged by the execution of Archbishop Salviati, excommunicated Lorenzo and placed all of Florence under interdict, then joined the Kingdom of Naples in open war against the city. The conflict dragged on for two years until Lorenzo took the considerable personal risk of travelling to Naples himself to negotiate directly with King Ferdinand I, securing peace through diplomacy rather than continued fighting. The episode ultimately strengthened Lorenzo's authority within Florence far beyond what it had been before the attack.

How is the conspiracy remembered?
Niccolò Machiavelli later wrote a detailed account of the conspiracy in his Florentine Histories, using it to explore how conspiracies succeed or fail depending on timing, secrecy, and public sentiment. The plot has remained a touchstone for historians studying Renaissance politics precisely because it combined religious ritual, high finance, and papal intrigue into a single violent afternoon. Its failure also illustrates how thoroughly the Medici had embedded themselves in Florentine loyalty by the late fifteenth century, despite holding no formal title to rule.

Why does it deserve a card?
The Pazzi Conspiracy captures Renaissance Florence at its most treacherous, a city where banking rivalries, papal politics, and family honour could converge into an assassination attempt carried out at the altar during Mass. It reveals how fragile even the most entrenched power could seem to its rivals, and how decisively that power could reassert itself when a plot failed. Few episodes show so clearly how the Medici ruled not through formal authority but through a loyalty the Pazzi fatally underestimated.

The Pazzi Conspiracy is part of Volume III

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