Vitellozzo Vitelli, the Tyrant of Citta di Castello, came to the aid of the Orsini, as did also the turbulent Baglioni of Perugia, the della Rovere in Rome, and all those who were inimical to Alexander VI.

On the other hand, however, the barons Colonna and Savelli ranged themselves on the side of the Pope.
Already Trevignano had fallen, and the attack of the pontifical army was concentrated upon Bracciano.

Hard pressed, and with all supplies cut off, Bartolomeo d'Alviano was driven to the very verge of surrender, when over the hills came Carlo Orsini, with the men of Vitellozzo Vitelli, to take the papal forces by surprise and put them to utter rout.

Guidobaldo was made prisoner, whilst the Duke of Gandia, Fabrizio Colonna, and the papal legate narrowly escaped, and took shelter in Ronciglione, the Pope's son being slightly wounded in the face.
It was a severe and sudden conclusion to a war that had begun under such excellent auspices for the Pontificals.

Yet, notwithstanding that defeat, which had left guns and baggage in the hands of the enemy, the Pope was the gainer by the campaign, having won eleven strongholds from the Orsini in exchange for one battle lost.
The barons now prepared to push home their advantage and complete the victory; but the Pope checkmated them by an appeal to Gonzalo de Cordoba, who promptly responded and came with Prospero Colonna to the aid of the Church.