Isabel married twice, successively to two identically named first-cousins, grandsons of
Thomas de Beauchamp, 11th Earl of Warwick: • Firstly to
Richard de Beauchamp, 1st Earl of Worcester (1394–1422) who died at the
Siege of Meaux. They had one daughter: •
Elizabeth de Beauchamp, born 1415, who married
Edward Neville, 1st Baron Bergavenny (died 1476), and had children. • Secondly to
Richard de Beauchamp, 13th Earl of Warwick (1382–1439), her 1st husband's first-cousin from a senior Beauchamp line, by whom she had two children: •
Henry de Beauchamp (1425–1446), who succeeded his father as 14th
Earl of Warwick, and later was created 1st
Duke of Warwick. He married Cecily Neville, daughter of
Richard Neville, 5th Earl of Salisbury, and had by her one daughter
Anne Beauchamp, 15th Countess of Warwick who died as a child. •
Anne de Beauchamp, who became 16th
Countess of Warwick, following the deaths of her brother and his infant daughter. Anne married
Richard Neville, the Kingmaker, eldest son of
Richard Neville, 5th Earl of Salisbury, and who became
jure uxoris 16th Earl of Warwick. Her husband therefore was the brother of her own brother's wife. They had two daughters who married at the highest level:
Isabel Neville (1451–1476), who married
George Plantagenet, 1st Duke of Clarence (1449–1478), and
Anne Neville (1456–1485), who married firstly
Edward of Westminster, Prince of Wales, and secondly
King Richard III (1483–1485). == Ancestry ==