The Florentines, who had engaged to furnish him with 300 men-at-arms and 2000 infantry, if he would help them to retake Pisa, had just retracted their promise because of Louis XII's threats, and had undertaken to remain neutral.

Frederic, who was holding back his troops for the defence of his own States, because he supposed, not without reason, that, Milan once conquered, he would again have to defend Naples, sent him no help, no men, no money, in spite of his promises.

Ludovico Sforza was therefore reduced to his own proper forces.
But as he was a man powerful in arms and clever in artifice, he did not allow himself to succumb at the first blow, and in all haste fortified Annona, Novarro, and Alessandria, sent off Cajazzo with troops to that part of the Milanese territory which borders on the states of Venice, and collected on the Po as many troops as he could.

But these precautions availed him nothing against the impetuous onslaught of the French, who in a few days had taken Annona, Arezzo, Novarro, Voghiera, Castelnuovo, Ponte Corona, Tartone, and Alessandria, while Trivulce was on the march to Milan.
Seeing the rapidity of this conquest and their numerous victories, Ludovico Sforza, despairing of holding out in his capital, resolved to retire to Germany, with his children, his brother, Cardinal Ascanio Sforza, and his treasure, which had been reduced in the course of eight years from 1,500,000 to 200,000 ducats.

But before he went he left Bernardino da Carte in charge of the castle of Milan.