Katherine Swynford, née de Roet (1350–1403), was the third wife of John of Gaunt, the powerful Duke of Lancaster, son of King Edward III. Her father was a Flemish herald serving Queen Philippa of Hainault. Katherine was thus fortunate to marry an English knight, Sir Hugh Swynford. She became governess to the daughters of John of Gaunt and then his lover. Considering her utter lack of financial or dynastic importance, it was a surprise that Gaunt married her in 1396. Their 4 children were legitimized by King Richard II and surnamed Beaufort. These individuals and their offspring played a key role in the Wars of the Roses. Katherine's sister Philippa married Geoffrey Chaucer.