Ferdinand I of Portugal - King

King

On the death of Peter of Castile in 1369, Ferdinand, as great-grandson of Sancho IV by the female line, laid claim to the vacant throne, for which the kings of Aragon and Navarre, and afterwards John of Gaunt, Duke of Lancaster (married in 1370 to Constance, the eldest daughter of Peter), also became competitors.

Meanwhile Henry II of Castile, Peter's illegitimate brother, who had defeated Peter, assumed his crown and took the field. After one or two indecisive campaigns, all parties were ready to accept the mediation of Pope Gregory XI. The conditions of the treaty, ratified in 1371, included a marriage between Ferdinand and Leonora of Castile. But before the union could take place Ferdinand had become passionately attached to Leonor Telles de Menezes, the wife of one of his own courtiers. Having procured a dissolution of her previous marriage, he lost no time in making Leonor his queen.

This strange conduct, although it raised a serious insurrection in Portugal, did not at once result in a war with Henry. However, the outward concord was soon disturbed by the intrigues of the Duke of Lancaster, who prevailed on Ferdinand to enter into a secret treaty for the expulsion of Henry from his throne. The war which followed was unsuccessful; and peace was again made in 1373. On the death of Henry in 1379, the Duke of Lancaster once more put forward his claims, and again found an ally in Portugal. According to the Continental annalists, the English proved as offensive to their allies as to their enemies in the field. So Ferdinand made a peace for himself at Badajoz in 1382. It stipulated that Beatrice, Ferdinand's daughter and heiress, would marry King John I of Castile, and thus secure the ultimate union of the two crowns.