Edward, the "Black Prince," was then brilliantly invading France and extending the kingdom of his father Edward III. He was the kinsman of Pedro, and when appealed to by his cousin for aid in protecting his kingdom from the King of Aragon and his French allies, Edward gallantly consented to help him; and in the spring of 1367, for the second time, a splendid army advanced through the Pass at Roncesvalles, and a great battle, worthy of a better cause, was fought and won. So this most atrocious king--perhaps excepting Richard III. of England, whom he resembled--had for his champion the victor of Cressy and Poictiers. He was restored to his throne, which had been usurped by his brother Enrique (or Henry), but in a personal encounter with Enrique soon after (which was artfully brought about by the famous Breton knight, Bertrand du Guesclin), he met a deserved fate (1369). Constanza, the daughter of Pedro the Cruel, had been married to John of Gaunt (Duke of Lancester), brother of the Black Prince and son of Edward III. As Constanza was the great-grandmother of Isabella I. of Spain, so in the veins of that revered Queen there flowed the blood of the Plantagenets, as well as that of Pedro the Cruel! Because of the number of doubtful pretenders always existing in Spain, disputes about the royal succession also always existed. Such a dispute now led to a long war with Portugal, where King Fernando had really the most valid hereditary claim to the throne made vacant by Pedro's death. If his right had been acknowledged, Portugal and Spain would now be united; Isabella would have remained only a poor and devout princess, and would never have had the power to win a continent for the world. So impossible is it to remove one of the links forged by fate, that we dare not regret even so monstrous a reign as that of Pedro the Cruel! Enrique's right to the vacant throne of his brother had two disputants. Besides the King of Portugal, John of Gaunt, who had married the lady Constanza,--by virtue of her rights as daughter of Pedro,--claimed the crown of Castile. This Plantagenet was actually proclaimed King of Castile and Leon (1386). For twenty-five years he vainly strove to come into his kingdom as sovereign; but finally compromised by giving his young daughter Catherine to the boy "Prince of Asturias," the heir to the throne. He was obliged to content himself by thus securing to his child the long-coveted prize. And it was this Catherine, who at fourteen was betrothed to a boy of nine, who was the grandmother of Isabella, Queen of Castile.