On 24 March 1500, La Trémoille joined the main French army at Mortara with a corps of about 6,000 men, supported by a numerous and powerful artillery. He was quickly followed by the 10,000 Swiss raised by the Baillie of Dijon. On 5 April, all the King’s army was united and marched to engage the Milanese forces before Novara. As we have seen, there was a large number of mercenary soldiers in the ranks of each of the two armies. The Helvetic cantons, in accepting their contracts, had it placed in the contracts that they would not be forced to fight against other Swiss. These troops were very close and, even though serving under different flags, would even drink together.
As a result of this, when on the 8th, the action began at Novara, Sforza’s Swiss refused to act against those of La Trémoille. It was a veritable defection, which produced, after a simple cannonade, the retreat of the Duke’s army, even though it was superior in numbers to the French army. Sforza and his army were obliged to go into the fortress of Novara, which was besieged by the French a few days later. La Trémoille, to cut his road to Milan, fortified himself between Novara and Tessin.
From the night of the 9th, the Swiss, in the service of Sforza, mutinied and negotiated a capitulation with the French. The German Landsknechts quickly did the same. By this capitulation, which was executed on 10 April 1500, the Swiss and Landsknechts were allowed to return to their homes with their baggage, after having laid down their arms. As for the Lombards and the stradiotes [Albanian and Greek light cavalry], who were their companions in arms, they were heartlessly abandoned to the mercy of the French. These unfortunates, thus sacrificed, came out of Novara and attempted to cut their way down the road to Tessin. They were charged and piteously torn to pieces by the French forces. During this butchery, the Swiss passed by pairs or threes before the French, where they were examined as the French searched for Sforza, who was thought to be concealed in their midst. He was cowardly surrendered by two of his companions, taken to France and locked up in the Loches Château, where he was held in a cage that was six feet wide and eight feet long. He was refused books for his amusement. By one of these providential reprisals such as history offers us so many examples, he who had held his unfortunate nephew captive for so many years, perished in his own turn in a captivity that lasted eight years; it was softened a little only on its end. The only consolation for Sforza that he had a château as a prison.