On September 29, 1364, two rival claimants to the duchy of Brittany met near Auray after twenty-three years of civil war. John of Montfort’s Anglo-Breton army held prepared ground. Charles of Blois advanced with Franco-Breton forces. By the end of the battle Charles was dead, Bertrand du Guesclin was a prisoner, and the Breton succession struggle had been decided on the field.
Part of the September 29 Today in History edition. Explore more in WAR & CONFLICTS.
A duchy without an uncontested heir
The crisis began in 1341 when Duke John III of Brittany died without a direct heir. Two claims dominated. John of Montfort asserted a right through the male line. Charles of Blois claimed through his wife, Joan of Penthièvre, a niece of the dead duke. The dispute was Breton, but it unfolded inside the Hundred Years’ War.
England supported the Montfort cause, while the French crown backed Charles of Blois. That alignment brought soldiers, commanders and resources from outside Brittany into a dynastic conflict. It also ensured that local control of ports and fortresses mattered to the larger rivalry between the English and French monarchies.
The war outlasted captures, truces and shifts in leadership. The elder John of Montfort died in 1345, leaving his young son to continue the claim. Charles of Blois had been captured at La Roche-Derrien in 1347 and spent years in English captivity before returning. By 1364 both parties had reason to seek a decisive result.
The siege that drew the armies together
Auray controlled an important position in southern Brittany. In 1364 Montfort’s forces besieged the town and its castle. Charles of Blois moved to relieve it with an army that included the experienced Breton commander Bertrand du Guesclin. John of Montfort was supported by Sir John Chandos, one of the most capable English captains of the period.
The surviving narratives do not provide modern certainty about exact troop numbers. Medieval chroniclers often shaped battle accounts around courage, rank and moral meaning, and later retellings have repeated estimates that should be treated cautiously. What is clear is the structure of the confrontation: a Montfortist force in a strong position faced an attempted relief by Charles’s army.
Negotiation did not prevent combat. The rival claims had become difficult to reconcile because each side treated ducal authority as indivisible. A compromise over territory or title would have required one claimant to surrender the political core of the dispute.
The fighting on September 29
Charles’s forces attacked the Anglo-Breton position. Accounts describe hard close fighting and the use of dismounted men-at-arms, a common feature of major fourteenth-century battles. Chandos helped organize the Montfortist line and reserve. The defenders absorbed the assault and then pressed the advantage as the opposing formation lost cohesion.
Charles of Blois was killed during the battle. Du Guesclin was captured and later ransomed. Their fates mattered beyond symbolism: the death of one claimant removed the central obstacle to a settlement, while the capture of a leading commander confirmed the completeness of the defeat.
The battle is sometimes compressed into a simple English victory over France. That description misses the Breton character of both armies. Bretons fought on each side for rival dynastic and political futures. English and French intervention shaped the struggle, but the cost was borne inside Brittany as well.
From battlefield to treaty
Auray did not itself create a legal settlement. That came with the Treaty of Guérande in 1365. Joan of Penthièvre renounced the immediate ducal claim, and John of Montfort was recognized as Duke John IV. The agreement included provisions intended to regulate succession and reconcile competing rights.
John IV’s victory did not make his rule effortless. His English connections could provoke suspicion among Breton elites and the French crown. He later faced exile and return. Auray established the dynasty, but political authority still had to be negotiated with nobles, towns and neighboring powers.
The battle nevertheless ended the long succession war’s central military contest. After more than two decades, one day of organized violence narrowed the range of possible constitutional outcomes.
How we know what happened
Battle narratives for Auray depend on chronicles, later manuscript traditions and the political memory of Brittany. Jean Froissart’s famous chronicles are invaluable but not transparent transcripts. They were literary histories written for elite audiences and revised across versions.
The featured image is a fifteenth-century manuscript illumination. It is historically important evidence for how later medieval readers imagined the battle, not a contemporaneous photograph-like record of the exact terrain, armor or formations on September 29, 1364.
Modern institutional catalogues, including the Bibliothèque nationale de France, securely identify the battle, date, opponents and manuscript tradition. This article keeps tactical claims broad where the evidence does not support minute-by-minute reconstruction.
Why Auray mattered
Auray linked a regional succession dispute to the international politics of the Hundred Years’ War. It demonstrates how dynastic law, marriage claims, local loyalties and foreign intervention could combine into a conflict that lasted a generation.
The death of Charles of Blois also changed the moral memory of the war. His supporters remembered his piety and sacrifice, while Montfortist victory produced its own dynastic narrative. Commemoration did not merely preserve the battle; it argued over the legitimacy of the duchy that followed.
For Brittany, September 29 was decisive not because every dispute vanished, but because the identity of the duke ceased to be an open military question. The battlefield made the treaty possible.
Command, terrain and the limits of reconstruction
Auray was not an encounter between anonymous national armies. Its commanders belonged to overlapping networks of lordship and military service. John of Montfort’s cause combined Breton adherents with English support; Charles of Blois drew Bretons who regarded his wife’s hereditary claim as legitimate and soldiers connected to the French crown. Labels such as “English” and “French” are useful shorthand, but they cannot fully describe the loyalties on the field.
Chandos’s experience mattered because fourteenth-century battles were organizational tests. Men-at-arms had to hold formation under pressure, reserves had to be committed at the right moment and commanders needed enough control to prevent a local reverse from becoming a rout. The surviving accounts credit the Montfortist position and cohesion without allowing a reliable modern map of every movement.
Terrain near Auray has changed, and later memorials have influenced how the location is remembered. The probable battlefield lies near the Chartreuse outside the town. A granite cross erected in the nineteenth century commemorated the battle, showing how a medieval succession struggle continued to shape Breton regional memory.
The fate of Charles of Blois also affected interpretation. His supporters emphasized his religious devotion, and a later campaign sought recognition of his sanctity. John IV’s dynasty, by contrast, had reason to frame victory as lawful resolution. Historical memory became another arena in which the rival claims continued after weapons were put down.
Auray therefore rewards caution about decisive battles. The combat removed one claimant and captured a major commander, but the political meaning was constructed afterward through treaty, ducal government and commemoration. A battlefield can narrow history’s possibilities; it does not write the whole settlement by itself.
