The reign of Juan II. is one of the longest and most troubled in the history of Castile. In his second year he succeeded his father, Enrique _el Doliente_, at the end of 1406, and for almost half a century he was the sport of fortune. Enrique III.’s frail body was tenanted by a masterful spirit: his son was a puppet in the hands of favourites or of factions. Juan II.’s uncle Fernando de Antequera (so called from his brilliant campaign against the Moors in 1410, celebrated in the popular _romances_) acted as regent of Castile till he was called to the throne of Aragón in 1412, when the regency was assumed by the Queen-Mother, Catherine of Lancaster. The generosity of contemporaries and the gallantry of elderly historians lead them to judge Queen-Mothers with indulgence; but Catherine is admitted to have been a grotesque and incapable figurehead, controlled by Fernán Alonso de Robles, a clever upstart. Declared of age in 1419, Juan II. soon fell under the dominion of Álvaro de Luna, a young Aragonese who had come to court in 1408, and had therefore known the king from childhood. Raised to the high post of Constable of Castile, Álvaro de Luna resolved to crush the seditious nobles, and to make his master a sovereign in fact as well as in name. But the king was a weakling who could be bullied out of any resolution. Factious revolts were met with alternate savagery and weakness. Opportunities were thrown away. The victory over the Moors at La Higuera in 1431, and the rout of the rebel nobles at Olmedo in 1445, failed to strengthen the royal authority. At a critical moment, when he seemed in a fair way to triumph, Álvaro de Luna made an irremediable mistake. In 1447 he promoted the marriage of Juan II. with Isabel of Portugal: she was ‘the knife with which he cut his own throat.’ At her suggestion the unstable Juan took a step which has earned for him a prominent place among the traitor-kings who have deserted their ministers in a moment of danger. Álvaro de Luna had fought a hard fight for thirty years. In 1453 he was suddenly thrown over, condemned, and beheaded amid the indecent mockery of his enemies:— Ca si lo ajeno tomé, lo mío me tomarán; si maté, non tardaran de matarme, bien lo sé. So even the courtly Marqués de Santillana holds up his foe to derision, unconscious that his own death was not far off. In 1454 Juan II. died, and during the scandalous reign of Enrique IV. it might well seem that the great Constable had lived in vain. But his policy was destined to be carried out by ‘the Catholic Kings,’ Ferdinand and Isabel.