Ferdinand, it is said, was so much dissatisfied with an arrangement which vested the essential rights of sovereignty in his consort, that he threatened to return to Aragon; but Isabella reminded him, that this distribution of power was rather nominal than real; that their interests were indivisible; that his will would be hers; and that the principle of the exclusion of females from the succession, if now established, would operate to the disqualification of their only child, who was a daughter. By these and similar arguments the queen succeeded in soothing her offended husband, without compromising the prerogatives of her crown.

Although the principal body of the nobility, as has been stated, supported Isabella's cause, there were a few families, and some of them the most potent in Castile, who seemed determined to abide the fortunes of her rival. Among these was the marquis of Villena, who, inferior to his father in talent for intrigue, was of an intrepid spirit, and is commended by one of the Spanish historians as "the best lance in the kingdom." His immense estates, stretching from Toledo to Murcia, gave him an extensive influence over the southern regions of New Castile. The duke of Arevalo possessed a similar interest in the frontier province of Estremadura. With these were combined the grand master of Calatrava and his brother, together with the young marquis of Cadiz, and, as it soon appeared, the archbishop of Toledo. This latter dignitary, whose heart had long swelled with secret jealousy at the rising fortunes of the cardinal Mendoza, could no longer brook the ascendency which that prelate's consummate sagacity and insinuating address had given him over the counsels of his young sovereigns. After some awkward excuses, he abruptly withdrew to his own estates; nor could the most conciliatory advances on the part of the queen, nor the deprecatory letters of the old king of Aragon, soften his inflexible temper, or induce him to resume his station at the court; until it soon became apparent from his correspondence with Isabella's enemies, that he was busy in undermining the fortunes of the very individual, whom he had so zealously labored to elevate. [11]

Under the auspices of this coalition, propositions were made to Alfonso the Fifth, king of Portugal, to vindicate the title of his niece Joanna to the throne of Castile, and, by espousing her, to secure to himself the same rich inheritance. An exaggerated estimate was, at the same time, exhibited of the resources of the confederates, which, when combined with those of Portugal, would readily enable them to crush the usurpers, unsupported, as the latter must be, by the co-operation of Aragon, whose arms already found sufficient occupation with the French.

Alfonso, whose victories over the Barbary Moors had given him the cognomen of "the African," was precisely of a character to be dazzled by the nature of this enterprise. The protection of an injured princess, his near relative, was congenial with the spirit of chivalry; while the conquest of an opulent territory, adjacent to his own, would not only satisfy his dreams of glory, but the more solid cravings of avarice. In this disposition he was confirmed by his son, Prince John, whose hot and enterprising temper found a nobler scope for ambition in such a war, than in the conquest of a horde of African savages. [12]

Still, there were a few among Alfonso's counsellors possessed of sufficient coolness to discern the difficulties of the undertaking. They reminded him that the Castilian nobles on whom he principally relied were the very persons who had formerly been most instrumental in defeating the claims of Joanna, and securing the succession to her rival; that Ferdinand was connected by blood with the most powerful families of Castile; that the great body of the people, the middle as well as the lower classes, were fully penetrated not only with a conviction of the legality of Isabella's title, but with a deep attachment to her person; while, on the other hand, their proverbial hatred of Portugal would make them too impatient of interference from that quarter, to admit the prospect of permanent success. [13]

These objections, sound as they were, were overruled by John's impetuosity, and the ambition or avarice of his father. War was accordingly resolved on; and Alfonso, after a vaunting, and, as may be supposed, ineffectual summons to the Castilian sovereigns to resign their crown in favor of Joanna, prepared for the immediate invasion of the kingdom at the head of an army amounting, according to the Portuguese historians, to five thousand six hundred horse and fourteen thousand foot. This force, though numerically not so formidable as might have been expected, comprised the flower of the Portuguese chivalry, burning with the hope of reaping similar laurels to those won of old by their fathers on the plains of Aljubarrotta; while its deficiency in numbers was to be amply compensated by recruits from the disaffected party in Castile, who would eagerly flock to its banners, on its advance across the borders. At the same time negotiations were entered into with the king of France, who was invited to make a descent upon Biscay, by a promise, somewhat premature, of a cession of the conquered territory.

Early in May, the king of Portugal put his army in motion, and, entering Castile by the way of Estremadura, held a northerly course towards Placencia, where he was met by the duke of Arevalo and the marquis of Villena, and by the latter nobleman presented to the princess Joanna, his destined bride. On the 12th of the month he was affianced with all becoming pomp to this lady, then scarcely thirteen years of age; and a messenger was despatched to the court of Rome, to solicit a dispensation for their marriage, rendered necessary by the consanguinity of the parties. The royal pair were then proclaimed, with the usual solemnities, sovereigns of Castile; and circulars were transmitted to the different cities, setting forth Joanna's title and requiring their allegiance. [14]

After some days given to festivity, the army resumed its march, still in a northerly direction, upon Arevalo, where Alfonso determined to await the arrival of the reinforcements which he expected from his Castilian allies. Had he struck at once into the southern districts of Castile, where most of those friendly to his cause were to be found, and immediately commenced active operations with the aid of the marquis of Cadiz, who it was understood was prepared to support him in that quarter, it is difficult to say what might have been the result. Ferdinand and Isabella were so wholly unprepared at the time of Alfonso's invasion, that it is said they could scarcely bring five hundred horse to oppose it. By this opportune delay at Arevalo, they obtained space for preparation. Both of them were indefatigable in their efforts. Isabella, we are told, was frequently engaged through the whole night in dictating despatches to her secretaries. She visited in person such of the garrisoned towns as required to be confirmed in their allegiance, performing long and painful journeys on horseback with surprising celerity, and enduring fatigues, which, as she was at that time in delicate health, wellnigh proved fatal to her constitution. [15] On an excursion to Toledo, she determined to make one effort more to regain the confidence of her ancient minister the archbishop. She accordingly sent an envoy to inform him of her intention to wait on him in person at his residence in Alcalá de Henares. But as the surly prelate, far from being moved by this condescension, returned for answer, that, "if the queen entered by one door, he would go out at the other," she did not choose to compromise her dignity by any further advances.

By Isabella's extraordinary exertions, as well as those of her husband, the latter found himself, in the beginning of July, at the head of a force amounting in all to four thousand men-at-arms, eight thousand light horse, and thirty thousand foot, an ill-disciplined militia, chiefly drawn from the mountainous districts of the north, which manifested peculiar devotion to his cause; his partisans in the south being preoccupied with suppressing domestic revolt, and with incursions on the frontiers of Portugal. [16]

Meanwhile Alfonso, after an unprofitable detention of nearly two months at Arevalo, marched on Toro, which, by a preconcerted agreement, was delivered into his hands by the governor of the city, although the fortress, under the conduct of a woman, continued to maintain a gallant defence. While occupied with its reduction, Alfonso was invited to receive the submission of the adjacent city and castle of Zamora. The defection of these places, two of the most considerable in the province of Leon, and peculiarly important to the king of Portugal from their vicinity to his dominions, was severely felt by Ferdinand, who determined to advance at once against his rival, and bring their quarrel to the issue of a battle; in this, acting in opposition to the more cautious counsel of his father, who recommended the policy, usually judged most prudent for an invaded country, of acting on the defensive, instead of risking all on the chances of a single action.