(1443). Lady Margaret Beaufort was the mother of King Henry VII and paternal grandmother of King Henry VIII of England. She was a key figure in the Wars of the Roses and an influential matriarch of the House of Tudor. She is credited with the establishment of two prominent Cambridge colleges, founding Christ's College in 1505 and beginning the development of St John's College, which was completed posthumously by her executors in 1511. Lady Margaret Hall, Oxford, the first Oxford college to admit women, is named after her and has a statue of her in the college chapel. She was the daughter and sole heiress of John Beaufort, Duke of Somerset, a legitimised grandson of John of Gaunt, 1st Duke of Lancaster by his mistress Katherine Swynford. Margaret was born at Bletsoe Castle, Bedfordshire, on either 31 May 1441 or, more likely, on 31 May 1443. The day and month are not disputed, as she required Westminster Abbey to celebrate her birthday on 31 May. The year of her birth is more uncertain. William Dugdale, the 17th-century antiquary, suggested that she may have been born in 1441, based on evidence of inquisitions post mortem taken after the death of her father. Dugdale has been followed by a number of Margaret's biographers; however, it is more likely that she was born in 1443, as in May 1443 her father had negotiated with the king concerning the wardship of his unborn child should he die on campaign. At the moment of her birth, Margaret's father was preparing to go to France and lead an important military expedition for King Henry VI. Somerset negotiated with the king to ensure that in case of his death the rights to Margaret's wardship and marriage would be granted only to his wife. As a tenant-in-chief of the crown the wardship of his heir fell to the crown under the feudal system. Somerset fell out with the king after coming back from France and was banished from the royal court pending a charge of treason against him. He died shortly afterwards. According to Thomas Basin, Somerset died of illness, but the Crowland Chronicle reported that his death was suicide. Margaret, as his only child, was heiress to his fortune. Upon her first birthday, the king broke the arrangement with Margaret's father and granted the wardship of her extensive lands to William de la Pole, 1st Duke of Suffolk, although Margaret herself remained in the custody of her mother. Margaret's mother was pregnant at the time of Somerset's death, but the child did not survive and Margaret remained the sole heir. Although she was her father's only legitimate child, Margaret had two maternal half-brothers and three maternal half-sisters from her mother's first marriage whom she supported after her son's accession to the throne. Margaret was married to Suffolk's son, John de la Pole. The wedding may have been held between 28 January and 7 February 1444, when she was perhaps a year old but certainly no more than three. However, there is more evidence to suggest they were married in January 1450, after Suffolk had been arrested and was looking to secure his son's future. Papal dispensation was granted on 18 August 1450, necessary because the spouses were too closely related, and this concurs with the later date of marriage. Margaret never recognised this marriage. Three years later, the marriage was dissolved and King Henry VI granted Margaret's wardship to his own half-brothers, Jasper and Edmund Tudor. In her will, made in 1472, Margaret refers to Edmund Tudor as her first husband. Under canon law, Margaret was not bound by the marriage contract as she was entered into the marriage before reaching the age of twelve. Even before the annulment of her first marriage, Henry VI chose Margaret as a bride for his half-brother, Edmund Tudor, 1st Earl of Richmond. Edmund was the eldest son of the king's mother, Catherine of Valois, by Owen Tudor. Margaret was 12 when she married the 24-year-old Edmund Tudor on 1 November 1455. The Wars of the Roses had just broken out; Edmund, a Lancastrian, was taken prisoner by Yorkist forces less than a year later. He died of the plague in captivity at Carmarthen on 3 November 1456, leaving a 13-year-old widow who was seven months pregnant with their child. Taken into the care of her brother-in-law Jasper, at Pembroke Castle, the Countess gave birth on 28 January 1457 to her only child, Henry Tudor, the future Henry VII of England. The birth was particularly difficult, because of her youth and small size. She never gave birth again. Margaret and her son remained in Pembroke until the York triumphs of 1461 saw the castle pass to Lord Herbert of Raglan.