Louis leaves Milan on April 15, 1509, at the head of a French army and moves rapidly into Venetian territory.
To oppose him, Venice has hired a condottiere army under the command of the Orsini cousins—Bartolomeo d'Alviano and Nicolo di Pitigliano—but had failed to account for their disagreement on how best to stop the French advance.
Consequently, when Louis crosses the Adda River in early May and Alviano advances to meet him, Pitigliano, believing it best to avoid a pitched battle, moves away to the south.
On May 14, Alviano confronts the French at the Battle of Agnadello; outnumbered, he sends requests for reinforcements to his cousin, who replies with orders to break off the battle and continues on his way.
Alviano, disregarding the new orders, continues the engagement; his army is eventually surrounded and destroyed.
Pitigliano manages to avoid encountering Louis; but his mercenary troops, hearing of Alviano's defeat, have deserted in large numbers by the next morning, forcing him to retreat to Treviso with the remnants of the Venetian army.
