The Castilian Succession Crisis: Afonso V’s Invasion…

The Castilian Succession Crisis: Afonso V’s Invasion and Marriage to Joanna la Beltraneja (1475)

Following the death of King Henry IV of Castile and León in 1474, a succession crisis erupted between two rival claimants:

1. Joanna la Beltraneja – Henry IV’s alleged daughter, supported by Portugal and a faction of Castilian nobles.
2. Princess Isabella of Castile – Henry IV’s half-sister, supported by her husband, Ferdinand of Aragon, and a rival faction of Castilian nobility.

The conflict led to the War of the Castilian Succession (1475–1479), a decisive struggle between Portugal and Castile, with France and Aragon also involved.

Afonso V’s Invasion of Castile and His Marriage to Joanna (1475)

• On May 10, 1475, King Afonso V of Portugal led an army into Castilian territory, launching an offensive to claim the Castilian throne.
• He advanced to Plasencia, where Joanna la Beltraneja awaited him.
• On May 25, 1475, Joanna and Afonso were proclaimed sovereigns of Castile, asserting their right to rule as king and queen.
• To strengthen his claim, Afonso married Joanna, despite being her uncle, making a Papal dispensation necessary.
• The required papal approval was granted several months later, reinforcing their legitimacy in the eyes of their supporters.

Consequences and the Prolonged Succession War

• Isabella and Ferdinand rejected the union, leading to full-scale war between Portugal and Castile-Aragon.
• The war lasted until 1479, with naval and land battles fought over the Castilian crown and Atlantic trade routes.
• Afonso’s lack of military aggressiveness and the stalemate at the Battle of Toro (1476) weakened Joanna’s claim.
• The war ended with the Treaty of Alcáçovas (1479), which:
  • Recognized Isabella and Ferdinand as rulers of Castile.
  • Confirmed Portugal’s dominance in the Atlantic, except for the Canary Islands.
  • Forced Joanna to renounce her claim and retreat to a convent in Portugal.

The failed campaign marked Portugal’s last attempt to unite with Castile, while Isabella and Ferdinand’s victory paved the way for the unification of Spain and their global expansion.