Pazzi-Verschwörung
The matter was solved by the election of Pope Sixtus IV, who married his favorite nephew Giovanni Della Rovere to Federico's daughter Giovanna, and gave him the title of Duke of Urbino in 1474; Malatesta married his other daughter Elisabetta. Now Federico fought against his former patrons the Florentines, caught in the Pope's attempt to carve out a state for his nephew Girolamo Riario. In 1478 Federico was involved in the Pazzi conspiracy.