[2] The early years of the reign of Isabella I were spent embroiled in a war of succession, as Henry IV had not specifically named a successor.

In 1480, Prince Afonso went to live in the town of Moura with his maternal grandmother Beatrice, Duchess of Viseu, and was joined in the early months of the following year by his future wife, the ten-year-old Isabella.

[6] Isabella also spent a considerable part of her youth on campaign with her parents as they conquered the remaining Muslim states in southern Spain.

Isabella proved a popular figure with the Portuguese royal family due to her knowledge of their language and customs brought about by the years she spent in Portugal as a child.

[11][12] She was heartbroken and later became convinced that he had died because God was angry that Portugal had provided a refuge for the Jews that her parents had expelled from Spain.

[14] There remained a stalemate between them until Princess Isabella agreed to marry Manuel on the condition that he expel all Jews from Portugal who would not convert to Christianity.

The Catholic Monarchs, to counter the pretensions of their son-in-law Philip, held courts in the city of Toledo in 1498 a few months after the death of their son John and had Isabella and her husband Manuel sworn as the legitimate heirs presumptive.

[18] Although female succession was permitted in Castile, Ferdinand II's kingdom of Aragon hesitated to accept a woman as their future ruler.

[19] Isabella was pregnant at that time and, while in Zaragoza with the royal family, she gave birth on 23 August 1498 to her only child, Miguel da Paz, Prince of Portugal.