The epithet "founder of Italian peace" relates to Pope Paul II's efforts at maintaining peace among the Italian States. Perhaps the most serious threat to peace came with the death of Francesco I Sforza on March 8, 1466. Upon hearing this news, a group of Florentine exiles in Venice conspired to overthrow the Sforzas in Milan. The condottiere Bartolomeo Colleoni, captain-general of the Republic of Venice, was employed and led a coalition force of 14,000 along with Ercole I d'Este of Ferrara. An army of 13,000 from Florence, Milan, Naples, and Bologna was led by Federico da Montefeltro of Urbino.

The two forces met on July 25, 1467, in Molinella, and the fighting yielded some 600 casualties, and nearly 1,000 horses were killed. Though indecisive, this was the first battle in Italy to feature large scale usage of artillery and firearms. After this battle, months were spent on military maneuvers and discussions without resolve. Worried of the threat posed by the Turks, Paul II determined to take it under his own authority to achieve peace, and insisted that Venice, Naples, Milan, and Florence to come to terms. With agreements made, Paul II proclaimed the peace among the Italian States in Rome on April 25, 1468, and the final conditions were officially drawn up by May 8.