The realization of his son’s marriage with Isabel of Castile, always favoured by him, was now his dearest ambition; for he believed that the final union of the two kingdoms would mean the death-blow to Louis XI.’s hopes of dominating the Pyrenees, as well as the building up of the power of the Crown at home against unruly subjects. Such designs were, however, of the future, while the immediate steps to achieve them were fraught with danger. Isabel, the bride-elect was at Valladolid, temporarily protected by the Archbishop of Toledo and the Admiral; but to the north lay the hostile Bishopric of Burgos, to the south-east a line of fortified strongholds, all in the hands of the Mendozas, the chief supporters of Joanna La Beltraneja and therefore enemies of the Aragonese match. It only needed the return of Henry IV. from Andalusia to make her position untenable. Isabel and the Archbishop of Toledo therefore dispatched messengers to Aragon in haste to insist that the King of Sicily should come to Valladolid. They found him in Saragossa, and suggested that, as every moment of delay increased the danger, he should disguise himself and go to Castile with only a few adherents, thus hoodwinking the Mendozas, who would never expect him to take this risk, and who also believed the negotiations for the marriage to be at a much earlier stage. Notwithstanding his later reputation for a hard head and a cool heart, Ferdinand in his youth possessed a certain vein of adventurous chivalry. It was with difficulty that he had been prevented from leading an entirely rash expedition to Isabel’s rescue at Madrigal, and he now readily agreed to a scheme, whose chief merit lay in its apparent impossibility. Sending one of the Castilian messengers on before to announce his coming, he and a few of the most trusted members of his household boldly crossed the frontier. The rest were disguised as merchants, Ferdinand himself as a servant; and at the inns where they were forced to halt he played his part, waiting at table and tending the mules. They did not stop often, riding in spite of the intense cold by day and night; with the result that they arrived before they were expected at the friendly town of Burgo de Osma. Ferdinand, whom excitement had rendered less tired and sleepy than the others, spurred forward as they came in sight of the gates, narrowly escaping death at the hands of an over-zealous sentry. Soon, however, their identity was explained, and amid the blowing of trumpets and joyful shouts the young King was welcomed by his allies. At Valladolid the news of his arrival into safe territory was the signal for feasting and jousts, and preparations for the marriage were pushed on apace. Ferdinand came by night to Valladolid, and, being met at a postern gate by the Archbishop of Toledo was led to the house where the Princess lodged.