marriage produced two children: Catherine of Lancaster (1372–1418)married Henry III of Castile, with whom she was a great-grandmother of Catherine of Aragon, first wife of Henry VIII of England. John (1374–1375) Constance died in 1394, after which John married Katherine Swynford on 13 January 1396. Their four children were born before they married. The pope legitimised them in 1396, as did Richard II by charter, on the condition that their children could not ascend the throne: John (c. 1371/1372–1410)grandfather of Margaret Beaufort, Henry VII's mother. Henry (1375–1447) Thomas (1377–1427) Joan (1379–1440)Joan's son, Richard Neville, 5th Earl of Salisbury, and her grandson, Richard Neville, 16th Earl of Warwick, were leading supporters of the House of York. Edmund (1341–1402)founder of the House of York. He had three children with Isabella of Castile: Edward (1373–1415)killed at the Battle of Agincourt. Constance (1374–1416) Richard(1375–1415) Blanche (1342)died as a child. Mary of Waltham (1344–1362)married John V, Duke of Brittany. No issue. Margaret (1346–1361)married John Hastings, 2nd Earl of Pembroke. No issue. Joan (b. 1351) Thomas (1355–1397)murdered or executed for treason by order of Richard II; his daughter, Anne, married Edmund Stafford. Edward's long reign had forged a new national identity, reinforced by Middle English beginning to establish itself as the spoken and written language of government. As a result, he is considered by many historians in cultural respects the first 'English' post-conquest ruler. Demise of the main line The Black Prince's ten-year-old son succeeded as Richard II of England on the death of his grandfather, nominally exercising all the powers of kingship, supported by various councils. His government levied poll taxes to finance military campaigns which, combined with the poor state of the economy, resulted in the Peasants' Revolt in 1381, followed by brutal reprisals against the rebels. The king's uncle Thomas of Woodstock, 1st Duke of Gloucester; Richard FitzAlan, 11th Earl of Arundel; and Thomas de Beauchamp, 12th Earl of Warwick; became known as the Lords Appellant when they sought to impeach five of the king's favourites and restrain what was increasingly seen as tyrannical and capricious rule. Later they were joined by Henry Bolingbroke, the son and heir of John of Gaunt, and Thomas de Mowbray, 1st Duke of Norfolk. Initially, they were successful in establishing a commission to govern England for one year, but they were forced to rebel against Richard, defeating an army under Robert de Vere, Earl of Oxford, at