The Treaty of Blois (1499), signed on 9 February 1499, was a secret military alliance between Louis XII of France and the Republic of Venice, in which they agreed to a joint attack on the Duchy of Milan.

[2] In August, he signed the Treaty of Marcoussis with Ferdinand II of Aragon; although it left outstanding territorial disputes between France and Spain unresolved, the two countries agreed to "have all enemies in common, except the Pope".

Under a deal brokered by Ercole I d'Este, Duke of Ferrara, Venice was granted Cremona along with lands on the eastern bank of the Adda, and agreed to pay part of Louis' expenses.

[5] Louis assembled an army of around 20,000 under Gian Giacomo Trivulzio, who invaded Milan in August 1499 while he remained in Lyons; with the bulk of Milanese forces in the western part of the duchy, the Venetians quickly occupied the eastern territories assigned to them by the treaty and captured Cremona on 8 September.

[9] As the new Duke of Milan, Louis could not escape the reality that Venice was its chief rival in Northern Italy and in 1508 France joined the anti-Venetian League of Cambrai, set up by Pope Julius II.