On May 9, 1386, the Treaty of Windsor was signed by which the kingdoms of Portugal and England were declared to be united henceforth in the closest bonds of friendship and alliance; and it proved to be the corner-stone of the policy of the House of Aviz. On July 20, 1386, John of Gaunt reached Corunna with two thousand English lances and three thousand archers, accompanied by his wife Constance of Castile, and two of his daughters, Philippa and Catherine. He marched triumphantly through Gallicia; and at Oporto on February 2, 1387, the Anglo-Portuguese Alliance was sealed by the marriage of King John to Philippa, the daughter of John of Gaunt by his first wife, Blanche of Lancaster. This marriage was followed by another, that of Catherine, only child of John of Gaunt by Constance of Castile to Henry, Prince of the Asturias, and heir to the throne of Castile. These marriages settled the peace of the peninsula, for in concluding them, John of Gaunt abandoned his claims to Castile, and insisted as one of the conditions, on a truce between his two sons-in-law. This truce continued till 1411, when at last the title of John as King of Portugal was recognized, and peace between Castile and Portugal was solemnly declared.
King John “the Great” was now firmly seated on his throne; an effort of his half-brother Diniz, the younger son of Ines de Castro, to overthrow him in 1398, failed entirely, and foreign monarchs hastened to recognize his power. Through this hero, and the race of heroes who fought under him, the independence of Portugal was secured, and a new career opened before its people. The era of consolidation was over; the era of foreign discovery and of Asiatic conquests was to begin.
