No more important epoch marks the history of Spain than the union of the crowns of Castile and Aragon; it meant the end of petty principalities and powers, it meant united Spain. But the crowns were only linked together, for Isabella, even in her marriage contract, had maintained the independence of the crown of Castile and her individual right to rule over it. It was this loyalty to her inherited crown that won the love and confidence of her people and made them ready, when the need came, to die for Isabella of Castile. And it was this independence of her crown that enabled her to say at last to Columbus: "I will assume the enterprise for mine own crown of Castile," and "to the crown of Castile" belonged the first discovered territories in the New World.
Had the reign of Isabella been less distinguished for events of such momentous magnitude as to involve the future interests of the world, her personal life would yet furnish data for a series of volumes, so replete was it with stirring incidents and with heart-breaking sorrows. But the same mental strength and moral courage that made her eminent as a queen, made her remarkable also as a friend and mother. Prescott says: "Her heart overflowed with affectionate sensibilities to her family and friends. She watched over the declining years of her aged mother and ministered to her sad infirmities with filial tenderness; we have abundant proofs of how fondly and faithfully she loved her husband to the last; while for her children she lived more than for herself, and for them too she died; for it was their loss and their afflictions which froze the current of her blood before age had had time to chill it."
Five children, four daughters and one son, grew to maturity under her guiding influence. Isabella, the first born, and ever the favorite child of the sovereigns, was born in 1470. She was twice married, first to Alfonso, Prince of Portugal, who was killed by a fall from his horse within five months after their marriage. Seven years later she married his brother, Emanuel, King of Portugal. To the intense grief of her husband, her parents, and her kingdom, she died in 1498, just one hour after the birth of her son, the first and only heir to the kingdoms of Castile, Aragon, and Portugal. The little Prince Miguel did not live to fulfil the hopes that were centred in him, for he died, to the great grief of the nation, before he had completed his second year.