Assertion of Royal Supremacy

When Afonso's son and heir, João II (r.1481-95), assumed the throne, the power of the Braganças and their supporters had reached its height. The new king, who was more resolute than his father, convoked a cortes at Évora, where he imposed a new written oath by which nobles swore upon their knees to give up to the king any castle or town they held from the crown. At Évora commoners complained about the abuses of the nobility and asked for the abolition of private justice and the correction of abuses in the collection of taxes. The king ordered that all nobles present their titles of privilege and that his constables be admitted to their estates in order to investigate complaints concerning administration.

These measures provoked a reaction by the nobility led by the powerful Fernando, duke of Bragança, who conspired against the king with the help of the king of Castile. Upon learning of the intrigues of Fernando, the king accused the duke of treason and tried him at a special court in Évora. He was sentenced to death and beheaded in the main square on June 29, 1484. The king confiscated his properties and those of his accomplices, some of whom were also killed, while others fled Portugal. A second conspiracy was hatched by the duke of Viseu, but it, too, was discovered, and the duke was killed, perhaps by the king himself, in Setúbal. These events established the supremacy of the crown over the nobility once and for all.