Polin succeeded ambassador Antoine de Rincon (1538–1541) in Constantinople. In early 1542, Polin successfully negotiated the details of a Franco-Ottoman alliance for the Italian War of 1542–1546, with the Ottoman Empire promising to send 27,500 troops against the territories of the Spanish king Ferdinand, as well as 110 galleys against Charles, while France promised to attack Flanders, harass the coasts of Spain with a naval force, and send 40 galleys to assist the Turks for operations in the Levant. Polin tried to convince Venice to join the alliance, but in vain.