Alfonso XI of Castile,
whose “favourite” was Leonora de Guzman. Being threatened with excommunication unless he put her away (as Leonora was in love with Ferdinando, a brave officer), the king created Ferdinando Marquis of Montreal, and gave him the hand of his mistress in marriage. As soon as Ferdinando discovered who Leonora was, he restored her to the king, and retired to a monastery. —Donizetti's Opera, La Favorita.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894