Thomas Beaufort, Duke of Exeter

Thomas Beaufort, Duke of Exeter, was one of the legitimised children of John of Gaunt and Katherine Swynford. He served Henry IV and Henry V as naval commander, chancellor and senior military officer and became one of the most trusted members of the Lancastrian regime. Beaufort fought in France, received custody of important prisoners and helped govern during Henry V’s campaigns. He died in 1426 without surviving legitimate children.

Thomas appears in Anya Seton’s Katherine as part of the Beaufort family and in historical fiction about Henry V and the Hundred Years’ War. He is usually a supporting figure rather than a protagonist. His career shows how legitimation transformed children born outside marriage into pillars of a royal dynasty while still leaving later uncertainty about succession rights.