The Life of Cesare Borgia by Rafael Sabatini

We come now to the consideration of an event which, despite the light that so many, and with such assurance, have shed upon it, remains wrapped in uncertainty, and presents a mystery second only to that of the murder of the Duke of Gandia.

It was, you will remember, in July of 1498 that Lucrezia took a second husband in Alfonso of Aragon, the natural son of Alfonso II of Naples and nephew of Federigo, the reigning king. He was a handsome boy of seventeen at the time of his marriage--one year younger than Lucrezia-- and, in honour of the event and in compliance with the Pope's insistence, he was created by his uncle Duke of Biselli and Prince of Salerno. On every hand the marriage was said to be a love-match, and of it had been born, in November of 1499, the boy Roderigo.