The Beaufort Bride
Arnopp, Judith

As King Henry VI slips into insanity and England teeters on the brink of civil war, a child is married to the mad king's brother. Edmund Tudor, Earl of Richmond, takes his child bride into Wales; a land of strife and strangers.
At Caldicot Castle and Lamphey Palace Margaret must acquire the dignity of a Countess and, despite her tender years, produce Richmond with a son and heir.
While Edmund battles to restore the king's peace, Margaret quietly supports his quest; but it is a quest fraught with danger.
As the friction between York and Lancaster intensifies, 14-year-old Margaret, now widowed, turns for protection to her brother-in-law, Jasper Tudor. At his stronghold in Pembroke, two months after her husband's death, Margaret gives birth to a son whom she names Henry, after her cousin the king.
The Beaufort Bride traces Margaret's early years from her nursery days at Bletsoe Castle to the birth of her only son in 1457 at Pembroke Castle. Her story continues book 2 & 3.