Cesare Borgia, duke of Valentinois, Italian Duca Valentino (born c. 1475/76, probably Rome [Italy]—died 1507, near Viana, Spain), natural son of Pope Alexander VI. He was a Renaissance captain who, as holder of the offices of duke of the Romagna and captain general of the armies of the church, enhanced the political power of his father’s papacy and tried to establish his own principality in central Italy. His policies led Niccolò Machiavelli to cite him as an example of the new “Prince.”