The quarter of a century during which the successor of John II., Emmanuel "the Fortunate," reigned, is the great heroic period of Portuguese history, and during it the great deeds, which make the Story of Portugal an important part of the history of Europe and of the world, were done. Discoveries and daring feats of arms distinguished nearly every year of this truly fortunate reign, and the fame of the great Portuguese generals, captains, and travellers is rivalled only by that of its poets and men of letters. As the progress of the Portuguese in the East and West, and their great literary development, will be examined in three different chapters, it will here be possible only to narrate the events of Emmanuel's reign in Portugal, and to show how, at the period of the greatest glory of the country, the age of its rapid decline was at hand. The causes of that decline were manifold, and are generally placed in the reign of Emmanuel's successor, but the seed of each appeared in the reign of the "fortunate" monarch himself.
Emmanuel himself contributed but little to the blaze of glory which illustrates his reign. He despatched great fleets and armies to distant parts of the world, and received the wealth their discoveries and exertions brought into his treasury with equanimity; but he had only one fixed idea, the old wild dream which had brought disaster upon Ferdinand "the Handsome" and Affonso V., the longing to sit upon the throne of Spain and to unite the kingdoms of the peninsula under his sovereignty. To gain this end he proposed to marry the Infanta Isabella, the eldest daughter of King Ferdinand of Aragon and Queen Isabella of Castile, and widow of the unfortunate Affonso, the only son of John II., and in order to be recognized as heir to the kingdoms of Spain, he promised to expel the Jews and unbaptized Moors from Portugal.