Borgia, Caesar, born 1476, was the fourth son of Pope Alexander VI. At the age of seventeen he was raised to the rank of cardinal, which he afterwards relinquished, and was made Duke of Valentinois by Louis XII., with whom his father had entered into an alliance against Naples. In 1499 he married the Princess Charlotte d'Albret, sister of the King of Navarre. At the head of a body of mercenaries he then engaged, on behalf of the Holy See, in a series of petty wars, made himself master of Romagna, Perugia, Siena, Piombino, Urbino,, and even threatened Florence, when his father died in 1503, and he himself fell ill. This was his enemies' opportunity, and he was arrested and carried to Spain, whence in 1506 he contrived to escape, and took refuge at the Court of Navarre. He afterwards served in the King of Navarre's army, and was killed in 1507 at the castle of Viana. Every species of crime has been ascribed to him, but whether truly or not it is difficult to say. Among his subjects he enjoyed the reputation of being just and upright, while he encouraged art and literature. It was Caesar Borgia that Machiavelli held in view when writing his Principe.