Constance married John (Plantagenet), of Gaunt, 1st Duke of Lancaster in Sept. 1371. John (son of Edward III (Plantagenet), King of England and Philippa (Avesnes), of Hainault) was born in March 1340 in St. Bavo's Abbey, Ghent, Belgium; died on 3 Feb. 1398/99 in Leicester Castle, Leicester, Leicestershire, England; was buried on 16 March 1398/99 in Old St. Paul's Cathedral, London, Middlesex, England. [Group Sheet] [Family Chart]

1. Katharine (Plantagenet), of Lancaster died on 2 June 1418.