Katherine married John Plantagenet, of Gaunt, 1st Duke of Lancaster in 1396. John (son of Edward Plantagenet, King Edward III and Philippa, of Hainault) was born on 6 Mar 1340 in Ghent, Flanders, Belgium; died on 3 Feb 1399 in Leicester Castle, Leicestershire; was buried in St Paul's Cathedral, London, England. [Group Sheet] [Family Chart]

1. John Beaufort, 1st Earl of Somerset
2. Cardinal Henry Beaufort
3. Thomas Beaufort, Duke of Exeter
4. Joan Beaufort, Countess of Westmorland