Feb. 24, 2004 — One of the most notorious crimes of the Renaissance, the attempted assassination of Florence's grandest son, Lorenzo dei Medici, has been solved more than 500 years later.
Known as the Pazzi conspiracy, the plot was led by Francesco dei Pazzi, whose banking family had resented for years the Medici climb to power.
The Pazzi plotted to kill Lorenzo and his brother Giuliano during a High Mass in the city's cathedral in April 1478. Wounded, Lorenzo managed to escape and barricade himself behind the bronze sacristy doors, but Giuliano bled to death on the cathedral floor.
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New findings now reveal that the plot was more than the result of a feud between two families. Behind the Pazzis lay a larger network of powerful conspirators who aimed to destroy Lorenzo the Magnificent and his expansionist ambitions for the Florentine state.
"One of the prime movers in the plot was none less than Federico da Moltefeltro, Duke of Urbino, always portrayed as a good friend of Lorenzo," Marcello Simonetta, a historian at Wesleyan University in Connecticut, told Discovery News.
The proof lies in a secret letter to Urbino's ambassadors in Rome that lay forgotten in the private Ubaldini archive. The letter was encrypted, but Simonetta had one advantage when he tried to decipher it: a 15th-century booklet written by an ancestor of his, explaining how to decode diplomatic correspondence.
"The letter reveals that Federico sent 600 of his well-trained troops to the gates of Florence. They were supposed to seize the city after the killing of the Medici brothers," Simonetta said.
Immortalized by Piero della Francesca in a stupendous, impassive portrait, Federico da Montefeltro was a great warrior and patron of the arts.
The portrait, an icon of the Renaissance, shows the Duke in all his imposing authority: a bull-necked man with raven hair slipping out from a red top hat, looking fiercely at his wife, represented in profile in another portrait.
"He has always been considered the ultimate humanist condottiero. Now we know he was involved personally in the conspiracy, inspired by Pope Sixtus IV and King Ferrante of Naples," Simonetta said.
Published in the Italian Historical Archives and in Simonetta's latest book, "Secret Renaissance: the World of the Secretary from Petrarch to Machiavelli," the decrypted letter has caused controversial reactions among historians.
"Simonetta's coded letter provides an interesting detail, namely, the Duke of Urbino's readiness to contribute 600 soldiers to the plot, but adds nothing of substance to what was already known.
"We already knew that the Duke was deeply involved in the conspiracy, that he was a soldier in the pay of Pope Sixtus IV, and that he had no love for Lorenzo il Magnifico. But he was certainly not the arch-conspirator.
This role belonged to Pope Sixtus, to Count Girolamo Riario, to the banker Francesco de' Pazzi, and even, perhaps, to the King of Naples," Renaissance scholar Lauro Martines, author of "April Blood: Florence and the Plot Against the Medici," told Discovery news.
According to Ronald Witt, professor of history at Duke University, Simonetta's discovery has indeed great historical importance.
"This is one of those rare finds that historians long to get their hands on. Although we knew well who the immediate perpetrators were, the letter reveals how elaborate and far-reaching the plot was," Witt told Discovery News.