In 1499 another French army marched over the Alps to invade northern Italy, deposing Ludovico Sforza (who eventually died in a French dungeon in 1508). Leonardo fled. He headed back to Florence, stopping briefly in Mantua to meet (and sketch) that city’s young and single-minded patron of the arts, Isabella d’Este, and in Venice to advise on defensive engineering to guard against possible invasion by the Ottomans.
