Edmund of Langley, 1st Duke of York, 1st Earl of Cambridge, KG (5 June 1341 – 1 August 1402) was a younger son of King Edward III of England and Philippa of Hainault, the fourth of the five sons who lived to adulthood, of this Royal couple. Like so many medieval princes, Edmund gained his identifying nickname from his birthplace: Kings Langley in Hertfordshire. At the age of twenty-one, he was created Earl of Cambridge. On 6 August 1385, Edmund was created Duke of York.[1] He was the founder of the House of York, but it was through the marriage of his younger son, Richard, that the Yorkist faction in the Wars of the Roses made its claim on the throne (the other party in the Wars of the Roses, the Lancasters, being the male descendants of his elder brother, John of Gaunt).
Marriage
Although marriages within the Royal Family and between Royal Families are the rule, it is interesting to note Langley's marital ties to his older brother, John of Gaunt. Langley's first wife, Infanta Isabella of Castile, was the sister of Gaunt's second wife, Infanta Constance of Castile; his second wife, Joan Holland, was the sister of Gaunt's daughter-in-law Margaret Holland, wife of Gaunt's son John Beaufort.
Langley's first wife, Isabella, was a daughter of King Peter of Castile and María de Padilla. They had two sons and a daughter:
- Edward of Norwich, 2nd Duke of York (killed in action at the Battle of Agincourt)
- Richard of Conisburgh, 3rd Earl of Cambridge (executed for treason by Henry V), ancestor of Kings Edward IV, Edward V, and Richard III of the House of York, and all succeeding monarchs of England after King Henry VII.
- Constance of York (an ancestor of Queen Anne Neville)
After Isabella's death in 1392, Langley married his cousin Joan Holland, whose great-grandfather Edmund of Woodstock, 1st Earl of Kent, was the half-brother of Langley's grandfather Edward II; she and Langley were thus both descended from King Edward I. The marriage produced no children.
http://en.wikipedia.org/wiki/Edmund_of_Langley