The battle occurred when Carlo I Malatesta, lord of Rimini, intervened in support of Alberico Novello da Barbiano, whose troops were under siege in the castle of Zagonara by Milanese mercenaries under Angelo della Pergola. Pergola had about 4,000 cavalry and 4,000 infantry. Malatesta's troops (amounting to some 8,000 cavalry) abandoned the siege of Forlì and attacked the Visconti, led by Secco da Montagnana.