Among prominent men with whom Francesco de’ Pazzi was thrown into contact were Archbishop Francesco de’ Salviati and Count Girolamo de’ Riari.  The Archbishop and Francesco were no strangers to one another; their families had risen to affluence and power side by side in Florence, actuated by like sentiments and engaged in like activities—­hatred of the Medici was mutual.

Sixtus had proposed, in 1474, to bestow upon Francesco de’ Salviati the Archbishopric of Florence, but the Signoria, instigated by Lorenzo, refused to confirm his appointment and declined to grant him the temporalities of the See.  The Pope yielded very ungraciously to the representations of the Florentine Government and named Rinaldo d’Orsini, Lorenzo’s brother-in-law, to the vacancy.  This intervention was adduced by Sixtus afterwards as insubordination worthy of punishment, and he did not forget to take his revenge.

The following year Francesco de’ Salviati was chosen as Archbishop-designate of Pisa, and again the Florentines objected—­being joined by the Pisans, who conspired to prevent him taking possession.  The Archbishop was, according to Agnolo Poliziano—­the devoted historian and poet-laureate of Lorenzo il Magnifico—­“An ignorant man, a contemner of all law—­human and divine—­a man steeped in crime, and a disgrace to his family and the whole State.”

Count Girolamo de’ Riari, accounted a nephew of Sixtus, was, like his elder brother Piero and Caterina his sister, a natural child of the Pope.  The three were treated with parental affection by the pontiff, and had their home in his private apartments, being waited upon by their unrecognised mother in the guise of nurse and guardian.

Piero de’ Riari was created a Cardinal when a spoilt boy, and became, as a man, infamous for his debauchery and villainy.  Sixtus had the effrontery to select him as successor to Archbishop Orsini in Florence, but his action was prompted by a motive, which was firmly fixed in his heart.  This was nothing less than the supplanting of Lorenzo de’ Medici by Piero or Girolamo!  So far, however, as Cardinal de’ Riari was concerned, Sixtus’ ambitions were wholly disappointed by his sudden death, due to violent excesses of all kinds.

Like his brother, Count Girolamo, the offspring of illicit lust, and brought up in the depraved atmosphere of the Papal court, was a reprobate; but Sixtus’ vaulting ambition stopped not at character and reputation.  He was bent upon the permanent aggrandisement of all the branches of the Delle Rovere family.  Casting about for territorial dignity, the Pope set his heart upon the Lordship of Imola, where Taddeo Manfredi of Faenza, being in financial difficulties, had surrendered the fief to the Duke of Milan.

The proposal to bestow the Lordship upon Count Girolamo de’ Riari by purchase was warmly resented by the Florentines.  Sixtus approached the question in a most underhand and suspicious manner.  He knew perfectly well that negotiations were on foot for the acquisition of the property and title by Lorenzo, on behalf of the Florentine Government.  Nevertheless he sent a secret mission to Galeazzo Sforza, Duke of Milan, offering the handsome sum of fifty thousand gold ducats, with a proviso, that the Duke should bestow the hand of his illegitimate daughter Caterina upon Girolamo.