BIOGRAPHICAL: claimant King of Castile; titular Duke of Aquitaine; dominated England during last years of King Edward III 's life.
John of Gaunt's armor in the Tower of London show his height as 6' 7". He played an important part in the wars of the period between England and France and between England and Spain. He commanded a division of the English army, led by the Black Prince, that defeated the army of Henry (later Henry II, king of Castile and León) at Najera in 1367.
As a result of his second marriage, to Constance, daughter of Pedro III the Cruel (king of Castile and León), John laid claim to the throne of Castile. During the Hundred Years' War, he aided (1370-71) the Black Prince against France and established English rule over most of southern France.
After a severe illness forced the return of the Black Prince to England, John took command of the English armies; by 1380 he had lost much of the territory the English had previously won. In 1386 John invaded Castile, but was defeated by John I, king of Castile and León. John of Gaunt gave up his claim to Castile and León in 1387, when his daughter married Henry, later Henry III, king of Castile and León.
John of Gaunt was also prominent in English affairs. Together with Alice Perrers (d. 1400), his father's mistress, John dominated the English government. His rule was opposed by Parliament and by the Black Prince.
In 1376 Parliament banished Alice Perrers and curtailed John's powers. The death of the Black Prince that year and the dissolution of Parliament, however, enabled John to regain his power. In 1377, on the death of Edward III and the accession of Richard II (John's nephew and son of the Black Prince), John gave up his control of the government and thereafter played the role of peacemaker; he also supported the king, by whom he was made (1390) duke of Aquitaine.
In 1396, after the death of his second wife, John married his mistress Catherine Swynford and Richard legitimized their children the following year. Saddened by the exile (1398) of his son, Henry of Lancaster (later King Henry IV of England), John died.