The Annotated Prince - The Prince by Niccolò Machiavelli with notes by Gene Gessert

The Pazzi Conspiracy (Sunday 26 April 1478)

Florence Cathederal
Cathedral of Saint Mary of the Flower in Florence, perhaps the world’s loveliest site of an assassination. Attribution: By Florian Hirzinger - (Own work) [CC BY-SA 4.0 (], via Wikimedia Commons.

When Machiavelli (1469 – 1527) was nine years old, a conspiracy culminated in an attack on the leading citizens of Florence, Lorenzo de’ Medci, known to history as Lorenzo the Magnificent (1419 -1492).  The attackers had aimed to kill both Lorenzo and his brother Giuliano.  The conspirators reasoned, correctly, that if they killed just Lorenzo, Giuliano would take his place and lead the Medici supporters in an orgy of vengeance.  The plotters made their attack at Sunday mass in the Cathedral of Saint Mary of the Flower Cattedrale di Santa Maria del Fiore).

For the conspirators, the outcome was worse than a failure, it was a blunder.  It killed only Giuliano, and left Lorenzo to inherit his younger brother’s wealth, to reap the benefit of sympathy, and with a pretext for taking draconian “remedial” action.  Lorenzo was not one to waste a crisis.  He capitalized on the incident to pass legislation the decisively tightened his grip on the city-state’s government, and launched extraordinary legal proceedings that purged the Pazzi from Florence.  Members of the family and their supporters were killed, or exiled, and financially ruined. 

Because the conspiracy materially changed the government of the city in which Machiavelli grew up, it would have made a lasting impression on his thinking.  Furthermore, conspiracies were far from novel in Renaissance Italy.  In fact the Pazzi conspiracy came only 16 months after another that killed the Duke of Milan, Galeazzo Maria Sforza. Machiavelli himself was implicated in a later conspiracy against another Medici regime.  All these incidents probably played a part in causing Machiavelli to devote the longest chapter in his book The Discourses (Book III Chapter VI, “Of Conspiracies)to a thorough discussion of the topic.  Here is a summary of his thinking:

  • Conspiracies are typically a means by which one party challenges the power and status of another. The challenger is often motivated by frustrated ambition (i.e., envy) and resentment over perceived slights.  Insults are particularly likely to trigger the irrational hatred that powers a plot.
  • Conspirators must be insiders who have knowledge, and position. Otherwise they cannot hope either to succeed at the act or to profit from its successful outcome.  Countermeasures should focus on insiders and place in their path obstacles that force them to lay elaborate (and therefore error-prone) plans. 
  • Conspiracies are vulnerable to detection because anyone who knows about it can profit by disclosing it to the intended victom.
  • Conspiracies are most vulnerable to detection in their planning stage.  Therefore, a successful conspirator must to the degree possible:
    • Plan alone.
    • Conspire with others only briefly.
    • Coerce co-conspirators to preempt defection.
  • The popularity of the intended victim works against the conspirator’s because it increases the chances that the conspirators will face retribution.
Leonardo da Vinci’s sketch of the conspirator who killed Giuliano hanged.
Leonardo da Vinci’s sketch of Bernardo di Bandino Baroncelli, the conspirator who killed Giuliano hanged. Attribution: Leonardo da Vinci [Public domain], via Wikimedia Commons.

The conspirators’ main target, Lorenzo, ruled Florence, not as its prince or as a constitutional executive, but only as its leading citizen. Florence was after all, formally at least, a Republic.  Lorenzo controlled the city by means of a coalition that was based on a patronage network.  His grandfather, Cosimo, had used the resources of the Medici bank to create the network, but once in place, it was self-sustaining.  Members of the coalition were able to pass vote-rigging laws that restricted critical city offices to those who were in the network.  Then, control of the city’s resources enabled the coalition to grant or withhold favors (especially tax breaks) and thus keep the system running.

To work correctly, however, the system had to remain closed. People who were outside the system would naturally envy the insiders, but there was little they could do.  An individual could only oppose the entire system or join it.  The only exception was a group of people that could form a rival coalition powerful enough to be a viable challenger.    The Pazzi family formed the core of just such a potential rival coalition. 

The Pazzi were a noble family that went into business and banking.  They became rich enough to rival the Medici in wealth and in the international scope of their organization.  The Pazzi were also prolific.  Lauro Martines tells us [p 97] that at the time of the conspiracy, there were 6 prominent adult males in the family.   To maintain its system, the Medici had to exclude the Pazzi men from power, honor, and status.  This contention led to an escalating series of incidents that both sides read as insults and challenges to their status.  In conformance with Machiavelli’s first point, this locking of horns, generated the irrational hatred that powered the plot. 

The culminating incident was a dispute between Medici Florence and the Papacy over the town of Imola. Florence wanted to buy the town from Milan, but Pope Sixtus IV wanted the city for his nephew, Count Girolamo Riario.  Sixtus made a bid for the city, which he tried to finance through the Medici bank.  Lorenzo refused the loan, but the Pazzi, sensing an opportune moment for a potential challenge, stepped in to make the loan.  Thus the Pazzi made common cause with the Pope, the Pope’s dependent allies (such as the Duke of Urbino), and other leaders such as King Ferrante of Naples, who viewed the Medici regime as an impediment to their power. 

The conspiracy proper was hatched in the summer of 1477 by three men:

  • Count Girolamo Riario – By then, Lord of Imola and Forli and the favorite of Pope Sixtus IV.
  • Francesco Pazzi – A leading member of the prominent, rich, and well connected Pazzi banking family.
  • Archbishop Saliviati – Archbishop of Pisa who was appointed by Pope Sixtus IV but opposed (out of spite) by Lorenzo.

These instigators, however, lacked both (A) the expertise to plan and execute the assassination, and (B) the armed force that would be necessary to pacify and seize the government after the assault so that they could profit by it.  The planning and execution they placed in the hands of an experienced soldier, the Count of Montesecco.  Montesecco was himself to kill Lorenzo and to recruit the other who would dispatch Piero, and provide cover for their escape.  The Pope and Duke Federigo were to supply armies to pacify the city after the coup.  
Note that, in violation of Machiavelli’s second principle, none of the conspirators were members of Lorenzo’s inner circle who had easy access to the family compound.  Worse still, the third principle was badly violated:

  • The key planner, Montesecco, did not work out the details before the instigators recruited the other plotters.  As a result the plans were not carefully made and rehearsed.
  • There were too many people involved in the plot to keep it secret for long. This created an urgency which forced the plotters into ad hoc measures in which they were obliged to change their plan of attack several times during the final days.

In the event, the only viable opportunity to kill both brothers was to attack at High Mass on Sunday in Florence’s main cathedral.  The change of venue to a holy site caused Montesecco to back out.  The instigators got two priests to make the necessary attack on Lorenzo, but they botched the job.

Lorenzo, was not loved by the political class, but he did cultivate a demagogic popularity with the masses. And, in accordance with Machiavelli’s fifth principle, after the coup failed, the common people formed themselves into a mob that (while relieving Lorenzo of any direct responsibility) cheerfully assisted him by taking indiscriminate bloody revenge on the conspirators, members of their families, and others.  On that April Sunday alone more than 60 people were killed (Martines p176).  In a more orderly process, Medici insiders, acting through “emergency” commissions killed, or exiled others who had or may have had some connection to the plot or at least to the plotters. 

Among those executed were Archbishop Saliviati and several priests. This gave Pope Sixtus a pretext to continue to pursue his agenda for regime change by military means.  The Holy Father organize a military coalition (including forces from Naples and Urbino), with the aim of deposing Lorenzo. After initial military successes, Sixtus’ coalition came undone when in December of 1479, Lorenzo went to Naples to treat with Duke Federigo.  By March 1480 Lorenzo was back in Florence with a peace deal in hand.  Sixtus may have fought on, but in the summer of 1480 the Ottoman Turks attacked Otranto, a port city on the heel of the Italian boot.  The threat motivated Sixtus to compose his differences with Lorenzo and set about organizing a defense.  Thereafter, Lorenzo continued as the unrivaled boss of Florence.