Manfredi, deceived by Caesar’s promises, instead of going to his friends and kinsmen in Bologna or Venice, accepted the Duke’s invitation to remain in his camp, and he probably stayed with Valentino until his arrival at the Vatican, June 17, 1501. A few days later he was flung into prison in the Castle of St. Angelo. After the fall of Faenza Valentino directed his attention to Giovanni Bentivoglio, demanding possession of Castle Bolognese in the name of the Pope. When Bentivoglio learned that Caesar was advancing with troops he dispatched ambassadors, who were promptly seized by Vitellozzo, who had captured the strongholds of San Pietro, Frumina, Guelfo, and Medicina. Bentivoglio, seeing that Caesar was determined, decided to yield, but he cunningly planned to secure him as an ally at the same time. April 30, 1501, Paolo Orsini negotiated a treaty between Caesar and Bentivoglio by which, in return for the surrender of Castle Bolognese, the former was to serve the latter as condottiere for three years with adequate pay, in all undertakings except such as might be directed against the King of France. Caesar was also to furnish a certain number of troops. Giulio and Paolo Orsini and Vitellozzo Vitelli signed the treaty for Caesar, who had remained at Medicina and who was for the first time designated as the Duke of Romagna in this document, his father having just conferred this title upon him. Caesar’s consent to this arrangement is explained by the fact that the King of France had demanded the return of his troops and the Pope had instructed Valentino to come to Rome without molesting the Florentines. Giuliano and Piero de’ Medici, anxious to recover possession of the city from which they had been expelled, proposed to enter into an alliance with Caesar. Giuliano joined him at Bologna, intending to remain on his staff as he advanced through Tuscany and rally his own adherents. Piero also came from Rome to join Caesar, who knew that their presence in his army and the hatred of his captains for Florence would constitute a menace to the Republic; he therefore refused to enter into any agreement with Piero, and on the way to Bisagno he compelled Giuliano to stop at Loiano. Notwithstanding this the Signory of Florence felt that he had some sinister purpose with respect to themselves, consequently they sent Machiavelli to watch and study Caesar’s movements.