Pazzi conspiracy
In the aftermath of the Pazzi conspiracy and the punishment of supporters of Pope Sixtus IV, the Medici and Florence earned the wrath of the Holy See, which seized all the Medici assets that Sixtus could find, excommunicated Lorenzo and the entire government of Florence, and ultimately put the entire Florentine city-state under interdict. When these moves had little effect, Sixtus formed a military alliance with King Ferdinand I of Naples, whose son, Alfonso, Duke of Calabria, led an invasion of the Florentine Republic, still ruled by Lorenzo.