About the year 1366, at the age of 16, Katherine married Hugh Swynford (1340-1372), an English knight from the manor of Kettlethorpe in Lincolnshire, and bore him at least two children; Thomas (1368-1432), Blanche (born 1370), and likely the Margaret Swynford (born c. 1369) who was nominated a nun at the prestigious Barking Abbey by the command of Richard II in 1377). Katherine then became attached to the household of John of Gaunt, Duke of Lancaster, ostensibly as governess to his two daughters (the sisters of the future Henry IV of England) by his first wife Blanche. Eventually, she became his official mistress, about 1373. Katherine's sister Philippa, a member of the household of Queen Philippa of Hainault, wife of Edward III, married the poet Geoffrey Chaucer, whose poem The Book of the Duchess commemorated Blanche's death in 1369.
Long after the death of his second wife Constance of Castile, John and Katherine married on 13 January 1396 in Lincoln Cathedral, three years before he died. The four children Katherine had borne John of Gaunt had been given the surname "Beaufort" and were already adults when they were legitimized by this marriage with papal approval. The Beauforts were later barred from inheriting the throne by a clause inserted into the legitimation act by their half-brother, Henry IV.
Katherine survived John by only four years, dying on May 10, 1403. (Since she was then dowager Duchess of Lancaster, there was a record of the exact day, as there was not for her birth, when she was of considerably lower rank). Her tomb, and that of her daughter Joan Beaufort, are under a carved-stone canopy in the sanctuary of Lincoln Cathedral, but their remains are no longer in them, because the tombs were despoiled in 1644, during the English Civil War, by the Roundheads.
Katherine Swynford 
