Mad War

The Battle of Saint-Aubin-du-Cormier, fought on August 6, 1488, was the decisive engagement of the Mad War. The French force of 15,000 inflicted casualties of 5,000–6,000 on the Breton-led coalition of 11,500 at a cost of roughly 1,500 of their own, a disparity indicating a comprehensive French battlefield victory. The Duke of Orléans, fighting on the Breton side against the French crown, was among those caught up in the defeat. The scale of the Breton losses effectively ended Brittany's capacity to resist French power, and the battle preceded the Treaty of Sablé later that same month, by which Duke Francis II of Brittany was compelled to accept terms that subordinated the duchy to French authority. Saint-Aubin-du-Cormier thus marked the terminal point of Breton military independence and set in motion the dynastic process that would lead to Brittany's union with France.