Constance was the daughter of
King Peter and
María de Padilla. Peter had secretly married María, but was forced to repudiate her. Their relationship endured throughout his subsequent marriages, however. Peter was killed in 1369 by his half-brother
Henry II, who then ascended the throne. Constance remained outside Henry's control, besieged at
Carmona, until 1371. On 21 September, at
Roquefort, near
Bordeaux,
Guienne, she married the English prince
John of Gaunt, 1st Duke of Lancaster. Constance's younger sister,
Isabella, married John's younger brother
Edmund of Langley, 1st Duke of York. John and Constance had a son, John (1374–1375), and a daughter,
Catherine. ==Claim==