When the Pope had declared that the lords of the Romagna, having failed to pay the annual tribute to the Holy See, were deprived of their possessions, Caterina Sforza set up the claim that the Holy See still owed her a large sum of money which had been due her husband as Captain of the pontifical army; she therefore announced that if they persisted she would resist, and her first move was to send her younger children and her jewels to Florence for safety.
Knowing in advance that her people, because of their hatred of the Riario, would betray her, she retired to the castle of Forli and, filling it with arms and munitions of war, calmly awaited the enemy.
When Caesar was still some distance from the city, delegates appeared in his camp and offered to surrender the town to him without resistance. The capitulation was signed November 26th and Valentino entered the city the following day.
The castle independently of the town was defended by Dionigi di Naldo, whose wife and children were held by Caterina Sforza as hostages in the stronghold of Forli. Naldo held out for some time, but was finally forced to surrender, and December 13, 1499, Cardinal Giovanni Borgia, legate for Romagna and Bologna, received the oath of fidelity to the Holy See, in the Church of S. Domenico in Imola.
The smaller places in the county of Imola having been captured without difficulty, Valentino advanced against Forli, December 15th. On learning of Caesar’s approach, Caterina, who had retired to the castle, dispatched her brother, Alessandro Sforza, to urge the citizens to resist, saying that she herself would fight to the last. They, however, refused, and she took advantage of the last moments to send her eldest son to Florence for safety. The citizens were determined to surrender, and they so informed both the Countess and Valentinois. The two commissioners—who never returned—had scarcely delivered their message when she directed her artillery on the city and partly demolished the town hall.
Caesar arrived before the gates of Forli December 17th, but refused to enter as conqueror until the articles of capitulation had been given him. Two days later he made his entry without opposition, the citizens preferring him to their lord, Girolamo Riario, who had burdened them with heavy taxes and administered the laws in the most partial manner.
The castle still held out and Caesar immediately began preparations for its capture. On Christmas Day Caterina raised the flag of Venice, the lion of St. Mark, to make the enemy believe that the republic was her ally, but Caesar was not deceived.
After attempting to make a breach, Valentino decided to try to effect an agreement of some sort, and for this purpose presented himself before the walls, where the Countess herself talked to him from the ramparts; but she refused all offers; the Duke made two other equally unsuccessful attempts, and did not open fire until December 28th.
The Countess succeeded in repelling all his attacks until January 12, 1500. She was everywhere on the ramparts encouraging and directing her men. When the outer walls were stormed, Caterina, before retiring to the keep—the last resort—ordered all the supplies to be set on fire, thinking thereby to compel the enemy to retreat, but it was too late, for Yves d’Allegre and his French company succeeded in forcing their way into the tower, and a Bourguignon, in searching the halls, found the heroic Countess of Forli surrounded by a band of her faithful people. Eager for the reward of twenty thousand ducats which had been offered for her capture alive, he declared her his prisoner.
That same evening the Countess left the fortress with the honours of war; she rode forth, mounted on her charger, between the Duke of Valentinois and Yves d’Allegre, who conducted her and her maids to the palace of the Numai.