The Children of Adam and Eve

John I was the son of Henry II and of his wife Juana Manuel of Castile, daughter of Juan Manuel, Prince of Villena, head of a younger branch of the royal house of Castile. He was the last Spanish monarch to receive a formal coronation.

His first marriage, with Eleanor of Aragon on June 18, 1375, produced most of his issue, including the future Kings Henry III of Castile and Ferdinand I of Aragon.

He ransomed Leon VI, the last reigning king of Armenia, from the Mamluks and out of pity granted him the lifetime lordship of Madrid, Villa Real and Andújar in 1383.

He had engaged in hostilities with Portugal. His first quarrel with Portugal was settled in 1382, and later, on May 14, 1383, he married with Beatrice of Portugal, daughter of King Ferdinand I of Portugal. On the death of his father-in-law(October 22, 1383), John endeavoured to enforce the claims of his wife, Ferdinand's only child, to the crown of Portugal. The 1383-1385 Crisis, a period of civil unrest and anarchy in Portugal, followed. He was resisted by supporters of therival for the throne John I of Portugal, and was utterly defeated at the battle of Aljubarrota, on August 14, 1385.

He also had to contend with the hostility of John of Gaunt, 1st Duke of Lancaster, who claimed the crown of Castile by right of his wife Constance, the eldest daughter of Peter of Castile. The king of Castile finally bought off the claim of hisEnglish competitor by arranging a marriage between his son Henry and Catherine, daughter of Constance and John of Gaunt, in 1387.

King John was killed at Alcalá on October 9, 1390 when he fell off his horse, while he was riding in a fantasia with some of the light horsemen known as the farfanes, who were mounted and equipped in the Arab style. His tomb is in the Chapel ofthe New Monarchs of the Cathedral of Toledo in Spain.