On April 26, 1478, during the Holy Easter Sunday Mass in the cathedral of Florence, a group of conspirators led by the Pazzi family murdered Giuliano de Medici and wounded his older brother Lorenzo. Known as the Pazzi Conspiracy, the assassination was the first step in a coup d’état to overthrow the Medici brothers as the unofficial rulers of the Florentine government. However, Jacopo Pazzi, the head of the Pazzi family, and his fellow conspirators, backed by Pope Sixtus IV and the King of Naples, failed to win the support of the population of Florence, who instead rallied to the defense of the Medicis.
Two Households in Fair Florence: The Origins of the Pazzi Conspiracy
“There was in Florence in those days a family, the Pazzi, who had grown most powerful,” wrote Niccolò Valori in his biography on Lorenzo de’ Medici. “And as often happens among the great, they, wishing to alter the state of things, set themselves against the house and the family of the Medici,” remarked the 15th-century author. “They thought of nothing but how to diminish the authority and supremacy of Lorenzo,” claimed Valori.
The Medici family became the de facto ruler of Florence in the 1430s, when Cosimo de’ Medici successfully defeated his opponents. While the city nominally retained its republican liberties and constitutional regime, Cosimo assumed informal control of the Florentine government, creating a Consiglio dei Cento (Council of the Hundred) composed of his most loyal allies.
The political prestige of the Medici family continued with Cosimo’s son, Piero, and was cemented by his grandson Lorenzo de’ Medici, later known as Il Magnifico (The Magnificent). The family’s influence stemmed from their vast financial resources, including the powerful Medici bank, whose branches were active in all European markets. Cosimo increased his already considerable wealth by securing the management of the papal accounts. He also obtained control of the papacy’s alum mines in Tolfa.
In 1469, when 20-year-old Lorenzo de’ Medici succeeded his father as informal head of Florence, another family was vying for prominence and political power. Headed by Jacopo Pazzi, the rival dynasty enjoyed a considerable following among the Florentine elite.
In a city where the most influential families expressed their civic pride and prominence through their patronage of the arts, the Pazzi Chapel in Santa Croce, an iconic example of early Renaissance architecture, embodied the Pazzis’ Florentine identity and public prestige. The rich coffins of the family bank funded the ambitious project designed by Filippo Brunelleschi, the same architect Cosimo de’ Medici entrusted with the ambitious construction of the dome of the city’s cathedral.
In 1460, the marriage of Bianca de’ Medici (Lorenzo’s sister) with Gugliemo Pazzi (Jacopo’s nephew) secured a kinship between the powerful families. The new union, however, did not end the rivalry between the Medicis and the Pazzis (ironically, the Italian word pazzi translates to “madmen”). Later, when the rift between the two dynasties had worsened, Lorenzo claimed that “everything [the Pazzi] have achieved in this city they owe to our house, towards which they show themselves ungrateful.”
As Lorenzo de’ Medici consolidated his power, the Pazzi family’s influence on the city’s government began to wane. The feud between the two rival households worsened in 1471 when the Gonfalonier of Justice, backed by the Pazzi, called for an alliance with the king of Naples. The Medicis saw the proposal as criticism against their longstanding coalition with Milan, the axis of their foreign policy. Lorenzo responded by politically isolating Jacopo Pazzi.
Political and Diplomatic Background
In his Storia d’Italia (History of Italy), 16th-century historian Francesco Guicciardini famously defined Lorenzo de’ Medici as the “needle” in the balance of power between the states of the Italian peninsula.
“Knowing that it would be very dangerous both for himself and for the Florentine republic if one of the great powers increased its strength, he sought by every means to make sure that Italian affairs were balanced,” wrote Guicciardini.
In a letter to Pier Filippo Pandolfini, Lorenzo emphasized his commitment to a diplomatic balance in the peninsula, remarking he “lost a brother and almost lost his life” protecting the triple alliance between Florence, Milan, and Venice.
Created in 1474, the political coalition between three of the most influential Italian states replaced the Lega Italica (Italian League), a political and military pact signed by Florence, Milan, Venice, Naples, and the Papal States in 1454 when the Peace of Lodi ended a long period of conflicts.
In the 1470s, however, the territorial ambitions of these neighboring states caused the crisis of the Italian League. The relations between the former allies worsened in 1474 when Pope Sixtus IV sent the papal troops, led by his nephew Giuliano della Rovere, to Città di Castello, a small town in Umbria. The pope’s soldiers had already entered the cities of Forlì and Spoleto.
Sixtus IV’s territorial ambitions alarmed Lorenzo de’ Medici, who feared the establishment of a papal stronghold at the borders of the Republic of Florence. To prevent Giuliano della Rovere from asserting his uncle’s authority on Città di Castello, Lorenzo opted to come to the Umbrian town’s aid, calling for the other members of the Italian League to back his anti-papal military effort. However, due to his strained relationship with the Duke of Milan, Ferdinando of Aragona, the king of Naples, opted to side with Sixtus IV. The pope hoped that the dissolution of the league would isolate Florence.
The head of the Medici family responded by promoting a triple alliance between Florence, Venice, and Milan. Formally announced in 1474, the new league divided the Italian peninsula into two opposing factions.
“And although war had not yet been ignited between them,” later remarked Niccolò Machiavelli, “nonetheless every day gave them new causes for igniting one; and the pontiff especially … strove to offend the state of Florence.”
In January 1475, Lorenzo de’ Medici celebrated his new diplomatic victory with an elaborate joust, where his brother Giuliano distinguished himself for his athleticism. The public event also had a clear political aim, reminding the Florentines of the Medicis’ wealth and prestige.
The Plot Against the Medicis
By the time Lorenzo de’ Medici and Sixtus IV clashed over Città del Castello, their relationship had already turned sour. In 1473, their power struggle became evident when the Medici bank refused to loan the pope the sum he needed to buy the city of Imola from the Sforza family, the lords of Milan. In the end, Sixtus IV was able to make the purchase with the assistance of the Pazzi bank. Lorenzo’s lack of support for the pope’s ambitions had severe consequences for the Medicis, who lost the management of the papal accounts to the Pazzis.
After the crisis over Imola, the Pazzi family became the center of an international coalition against Lorenzo de’ Medici. The conspirators’ hostility toward Lorenzo increased in 1475 when the Florentine government protested the appointment of Francesco Salviati, a nephew of Jacopo Pazzi, as archbishop of Pisa, claiming that Sixtus IV had chosen him without any previous consultation with Florence.
In 1476, the murder of Count Galeazzo Maria Sforza in Milan weakened the geopolitical system of the Italian peninsula, strengthening the resolve of the Medici’s enemies to overthrow their rule in Florence. The already tense situation worsened the following year. In March, Lorenzo lobbied for a new inheritance law (De testamentis) that favored male descendants over females. The decree was especially damaging for the Pazzi family as Beatrice Pazzi, wife of Giovanni Pazzi, was prevented from inheriting the considerable fortune of her father, Giovanni Borromeo.
When the Florentine government passed the law, a plot to eliminate the Medici brothers was already well underway. According to Guicciardini and Machiavelli, the masterminds behind the Pazzi Conspiracy were Count Girolamo Riario, a nephew of Sixtus IV, and Francesco Pazzi, nephew of Jacopo Pazzi and manager of the family bank’s branch in Rome. Soon, other powerful opponents of the Medici regime joined Riario and Pazzi.
In 1475, King Ferdinando of Naples openly expressed his support for the Medici’s main Florentine rivals by appointing Antonio Pazzi archbishop of Sarno, a town in Campania. Meanwhile, the sovereign sent his loyal agents to Florence, instructing them to urge the population to rebel against the Medicean “tyranny.” Federico da Montefeltro, a mercenary general made Duke of Urbino by Sixtus IV, aided Ferdinando’s anti-Medicean activities. In 1478, Montefeltro, then an active participant in the Pazzi Conspiracy, agreed to send six hundred of his men as military support for the coup.
The conspirators also recruited Giovanni Battista, Count of Montesecco, an experienced military officer. After his arrest, the count gave a detailed account of the backstage machinations of the intrigue. In particular, Montesecco recalled a meeting with Sixtus IV, thus confirming the pope’s involvement in the Pazzi Conspiracy. He later made two secret trips to Florence to persuade Jacopo Pazzi to join the anti-Medicean plot.
A Murder in the Cathedral
In 1478, the conspirators were ready to set their plan into motion. Initially, they intended to kill Lorenzo de’ Medici during his visit to Rome during the Easter season. However, the young Medici unexpectedly canceled the trip. Then, on April 25, Lorenzo invited Francesco Salviati and 17-year-old Cardinal Raffaele Riario to his villa in Fiesole, hoping to repair his strained relations with the pope. Scholar Jacopo Bracciolini and Bernardo Bandini Baroncelli, the future assassin of Giuliano de’ Medici, were also present at the luncheon. During the festivities, Lorenzo invited his guests to attend the High Mass in honor of Cardinal Riario, which would take place the following day.
The invitation led the Medici’s enemies to postpone their planned coup, “and besides, they doubted that Giuliano would be eating there,” remarked Guicciardini. On April 26, Lorenzo entered the cathedral with Raffaele Riario. He was later joined by his younger brother. At an agreed-upon signal, the designated assassins assaulted the Medici brothers. Giuliano quickly fell under the blows of Bernardo Bandini Baroncelli and Francesco Pazzi. Baroncelli then tried to stab Lorenzo. He was saved by his friend Francesco Nori, who died protecting him. Amid the ensuing chaos, a wounded Lorenzo took refuge in a chapel.
Meanwhile, Jacopo Pazzi and Francesco Salviati tried to set into motion the second part of the coup by taking control of the Palace of the Priors. At the head of a group of armed men, the Pazzi patriarch attempted to stir a public uprising against the Medicis. However, it soon became apparent that the population would not back the putsch. As the Pazzi’s supporters shouted the slogan “People and Freedom,” a growing crowd of Medicean partisans responded by chanting Palle! Palle! (Balls! Balls!), a reference to the six red globes adorning the Medici family’s coat of arms.
A Bloody Reprisal
A few hours after the attack against the Medici brothers in the Duomo, a violent reprisal began. Amid the temporary dismantlement of the ordinary rule of law, the Medici family’s supporters arrested and summarily executed the conspirators. Archbishop Salviati, Francesco Pazzi, and Jacopo Bracciolini were hung from a window of Palazzo Vecchio. The bloodshed continued for weeks as angry mobs targeted even those who were only remotely associated with the Pazzi Conspiracy.
Jacopo Pazzi initially managed to flee the city. However, he was captured in the village of San Godenzo on April 29. After his execution, his body was put on display on the facade of Palazzo Vecchio. Captured on May 4, Count Montesecco was spared the humiliation of a public hanging. After giving his eyewitness account to the Florentine authorities, he was executed by beheading.
Bernardo Bandini Baroncelli, Giuliano’s killer, escaped to Constantinople, where he was arrested in 1479. Leonardo da Vinci, an eyewitness of his execution on December 29, reproduced the scene in a sketch. Badini Baroncelli and the other conspirators were also depicted by Sandro Botticelli in a series of paintings later displayed in the palace of the city’s magistrate. Under Baroncelli’s portrait, an inscription, composed by Lorenzo de’ Medici himself, declared: “I am Bernardo Badini, a new Judas / a Traitor and killer in a church was I / A rebel awaiting a more cruel death.” Ten years after the Pazzi Conspiracy, Count Girolamo Riario, the only architect of the plot still living, was murdered in Forlì, his body thrown out of a window of the government palace.
Florence After the Pazzi Conspiracy
The failure of the Pazzi Conspiracy strengthened Lorenzo de’ Medici’s prestige, cementing his role as de facto ruler of Florence. To fortify his political position, Lorenzo launched a propaganda campaign emphasizing his close relationship with the city. In his historical reconstruction of the event, written in the immediate aftermath of the plot, leading humanist Angelo Poliziano depicted his friend Lorenzo as the heroic savior of Florence.
Conversely, Poliziano described the Pazzi family as social and political outcasts, exaggerating their moral flaws.
“He was a bloodthirsty person,” wrote Poliziano about Francesco Pazzi, “… and the sort who, once he desired something in his heart, would go after it undeterred by considerations like honor, piety, fame, or reputation.”
While the early accounts of the coup centered on the role played by the Pazzis, there was no mention of the involvement of Sixtus IV and the king of Naples. Their names were also removed from public records. Only an anonymous poem commemorating the death of Giuliano de’ Medici alluded to the complicity of the two heads of state: “There were some people of high status whose name I should not mention, but they were capable of such evil misdeeds that everyone can figure out who they actually are.”
The Pazzi Conspiracy worsened relations between the city and Sixtus IV. Enraged by the public hanging of priests, the pope excommunicated Lorenzo de’ Medici and issued an interdiction against the city of Florence. When the Florentine government rejected his request to hand Lorenzo over to him, Sixtus IV, backed by Ferdinando of Aragona, sent his troops to Tuscany.
The following conflict, known as the War of the Pazzi, lasted two years. As the military expenses threatened to empty the city’s treasury, Lorenzo de’ Medici initiated peace negotiations with Ferdinando of Aragona in December 1479. The following year, Florence and Naples agreed to cease the hostilities. Sixtus IV ended the war against Lorenzo only in 1480 when the Ottomans’ conquest of Otranto shifted his attention to the newest threat.
