John III, Duke of Brittany

John III, known as the Good, was Duke of Brittany from 1312 until his death and the 5th Earl of Richmond from 1334 until his death. He was the offspring of Arthur II, Duke of Brittany, and Marie, Viscountess of Limoges. John staunchly opposed his father’s second marriage to Yolande, even attempting to challenge its legality.

Throughout his life, John had three marriages, all of which were childless. His reluctance to bequeath the Duchy of Brittany to his half-brother John of Montfort led to his preference for leaving it to the French King Philip VI, despite objections from his nobles. His niece’s marriage to Charles of Blois brought forth a competing claim for the duchy, which remained unresolved at the time of John’s demise. After his death, the Breton War of Succession ensued, contributing to the larger conflict of the Hundred Years’ War.