In 1447, John of Aragon contracted a second alliance with Joan Henriquez, of the blood royal of Castile, and daughter of Don Frederic Henriquez, admiral of that kingdom; [8] a woman considerably younger than himself, of consummate address, intrepid spirit, and unprincipled ambition. Some years after this union, John sent his wife into Navarre, with authority to divide with his son Carlos the administration of the government there. This encroachment on his rights, for such Carlos reasonably deemed it, was not mitigated by the deportment of the young queen, who displayed all the insolence of sudden elevation, and who from the first seems to have regarded the prince with the malevolent eye of a step-mother.
Navarre was at that time divided by two potent factions, styled, from their ancient leaders, Beaumonts and Agramonts; whose hostility, originating in a personal feud, had continued long after its original cause had become extinct. [9]
The prince of Viana was intimately connected with some of the principal partisans of the Beaumont faction, who heightened by their suggestions the indignation to which his naturally gentle temper had been roused by the usurpation of Joan, and who even called on him to assume openly, and in defiance of his father, the sovereignty which of right belonged to him. The emissaries of Castile, too, eagerly seized this occasion of retaliating on John his interference in the domestic concerns of that monarchy, by fanning the spark of discord into a flame. The Agramonts, on the other hand, induced rather by hostility to their political adversaries than to the prince of Viana, vehemently espoused the cause of the queen. In this revival of half-buried animosities, fresh causes of disgust were multiplied, and matters soon came to the worst extremity. The queen, who had retired to Estella, was besieged there by the forces of the prince. The king, her husband, on receiving intelligence of this, instantly marched to her relief; and the father and son confronted each other at the head of their respective armies near the town of Aybar. [10] The unnatural position, in which they thus found themselves, seems to have sobered their minds, and to have opened the way to an accommodation, the terms of which were actually arranged, when the long-smothered rancor of the ancient factions of Navarre thus brought in martial array against each other, refusing all control, precipitated them into an engagement. The royal forces were inferior in number, but superior in discipline, to those of the prince, who, after a well contested action, saw his own party entirely discomfited, and himself a prisoner. [11]