For 10 points, name this Valois king of France who lost to Charles V at the Battle of Pavia.
This ruler bemoaned "all is lost save honor" in a letter to his mother, Louise of Savoy, while in captivity. The ambassador Antonio Rincon was sent by this ruler to the court of Suleiman the Magnificent to negotiate an alliance with the Ottoman Empire. The Treaty of Cambrai removed this ruler's country from the War of the League of Cognac. Leonardo da Vinci spent his last years under the patronage of this ruler, who brought the Mona Lisa to his country. In an extravagant meeting that lasted two weeks long, this ruler attempted to form an alliance with Henry VIII at the Field of the Cloth of Gold. For 10 points, name this Valois king of France who lost to Charles V at the Battle of Pavia.
This ruler bemoaned "all is lost save honor" in a letter to his mother, Louise of Savoy, while in captivity.
Francis I [prompt on Francis]