John Of Gaunt (or Ghent), duke of Lancaster, fourth son of Edward III., born in Ghent in 1340, died Feb. 3, 1399. He distinguished himself for valor in the wars of his brother the Black Prince in France, and succeeded to his government in that country. In 1359 he married the lady Blanche, daughter and heiress of Henry Plantagenet; she bore him a son who in 1399 became the first English king of the house of Lancaster, as Henry IV. After her death he married in 1370 Constance, daughter of Pedro the Cruel of Castile, and assumed the arms and title of king of Castile, but returned to England within less than a year after his brother. There he defended Wycliffe, and was often suspected of aiming at the crown. He resigned his pretensions to the throne of Castile when his daughter Catharine married the heir apparent of that kingdom. John of Gaunt's third wife was Catharine Swynford, governess of his children, by whom he had three sons and one daughter before their marriage. These were legitimated, and one of them, John de Beaufort, earl of Somerset, was an ancestor of the Tudors.