1911 Encyclopædia Britannica/John I. of Portugal
JOHN I. (1357–1433), king of Portugal, the natural son of Pedro I. (el Justicieiro), was born at Lisbon on the 22nd of April 1357, and in 1364 was created grand-master of Aviz. On the death of his lawful brother Ferdinand I., without male issue, in October 1383, strenuous efforts were made to secure the succession for Beatrice, the only child of Ferdinand I., who as heiress-apparent had been married to John I. of Castile (Spain), but the popular voice declared against an arrangement by which Portugal would virtually have become a Spanish province, and John was after violent tumults proclaimed protector and regent in the following December. In April 1385 he was unanimously chosen king by the estates of the realm at Coimbra. The king of Castile invaded Portugal, but his army was compelled by pestilence to withdraw, and subsequently by the decisive battle of Aljubarrota (Aug. 14, 1385) the stability of John’s throne was permanently secured. Hostilities continued intermittently until John of Castile died, without leaving issue by Beatrice, in 1390. Meanwhile the king of Portugal went on consolidating the power of the crown at home and the influence of the nation abroad. In 1415 Ceuta was taken from the Moors by his sons who had been born to him by his wife Philippa, daughter of John, duke of Lancaster; specially distinguished in the siege was Prince Henry (q.v.) afterwards generally known as “the Navigator.” John I., sometimes surnamed “the Great,” and sometimes “father of his country,” died on the 11th of August 1433, in the forty-eighth year of a reign which had been characterized by great prudence, ability and success; he was succeeded by his son Edward or Duarte, so named out of compliment to Edward III. of England.
See J. P. Oliveira Martins, Os filhos de D. João I. and A vida de Nun’ Alvares (Lisbon, 2nd ed. 1894).