York, Edmund of Langley, duke of, 1341–1402, fifth son of Edward III of England. He was made (1362) earl of Cambridge, served on expeditions to Spain and France, and married (1372) Isabel, daughter of Peter the Cruel, king of Castile. He became (1377) a member of the council of regency for his nephew Richard II and in 1381–82 made a fruitless expedition to help Ferdinand I of Portugal against John I of Castile. He served against the Scots in 1385, and in that year he was created duke of York. He acted as regent when Richard II went to Ireland in 1394–95 and again in 1399. When Henry of Lancaster landed in England in 1399, to claim the throne, Edmund opposed him halfheartedly and finally veered to his support. After Henry's coronation as Henry IV, York retired from court. The royal house of York takes its name from his creation as duke of York.