Breton War of Succession

War of the Breton Succession
Part of Hundred Years' War
Battle of Auray
Date 1341-12 April 1365 Location Brittany Result Montfort military victory French strategic and political victory
Belligerents
Kingdom of France House of Blois Kingdom of Castile	Kingdom of England House of Montfort
Commanders and leaders
Charles of Blois  †	John of Montfort  † Joanna of Flanders John IV, Duke of Brittany Sir Thomas Dagworth
Strength
Unknown	Unknown
Casualties and losses
heavy	heavy

The War of the Breton Succession was a conflict between the Counts of Blois and the Montforts of Brittany for control of the Duchy of Brittany. It was fought between 1341 and 12 April 1365.

The war formed an integral part of the early Hundred Years' War due to the involvement of the French and English governments in the conflict; the French supported the Blois (female heir) whilst the English backed Montfort (male heir). The rival kings supported the duke of the principle opposite to their own claims to the French throne—the Plantagenet having claimed it by female succession, and the Valois by male succession. From a legal point of view, Blois had the superior claim, since Brittany allowed succession in the female line. Although Montfort was ultimately successful following the Battle of Auray in 1364, it was the French who gained the most from his victory.

The dukes had both a historical and ancestral connection to England and were also Earls of Richmond in Yorkshire. Duke Arthur II of Dreux married twice, first to Mary of Limoges (1275–1291), then to Yolande of Dreux (1263–1322), countess of Montfort and widow of king Alexander III of Scotland. From his first marriage, he had three sons, including his heir John III and Guy, count of Penthièvre (d. 1331). From Yolande, Arthur had another son, also named John, who became count of Montfort. (See Dukes of Brittany family tree.)

John III strongly disliked the children of his father's second marriage. He spent the first years of his reign attempting to have this marriage annulled and his half-siblings bastardized. When this failed, he tried to ensure that John of Montfort would never inherit the duchy. Since John III was childless, his heir of choice became Joan of Penthièvre, la Boiteuse, daughter of his younger brother Guy. In 1337 she married Charles of Blois, the second son of a powerful French noble house and son of the sister of King Philip VI of France. But in 1340, John III reconciled himself with his half-brother, and made a will that appointed John of Montfort the heir of Brittany. On 30 April 1341, John III died. His last words on the succession, uttered on his deathbed, were, "For God's sake leave me alone and do not trouble my spirit with such things".

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