The Battle of Auray, fought between Anglo-Breton forces and the Franco-Breton army, was a significant engagement during the War of the Breton Succession. This conflict arose after the death of Duke John III of Brittany, leading to a dispute over the rightful heir to the duchy. Supported by England, the Anglo-Breton forces were led by Charles of Blois, while the competing faction, loyal to the House of Montfort, was bolstered by backing from the French crown.

As the two sides clashed, the battle showcased the strategic prowess of the Anglo-Breton alliance. The French army was more numerous but struggled with coordination against the well-prepared Anglo-Breton troops. The use of archers and dynamic cavalry maneuvers proved instrumental for the Anglo-Bretton forces in securing victory. Key figures like the Montfortian leader John IV also played an essential role, influencing both the immediate outcome and the broader implications for Brittany's governance.

The aftermath of this decisive victory culminated in the Treaty of Guerande in 1365, which recognized John IV as the rightful Duke of Brittany, thereby stabilizing the region under Anglo-Breton influence. This battle not only determined the future of the duchy but also tightly intertwined the fates of England and Brittany, illustrating the far-reaching effects of regional conflicts during the Hundred Years' War.