John III of Brittany was a Duke of Brittany who reigned from 1341 to 1364. He was born in 1286 and was the son of John II of Brittany. His reign was marked by the Breton War of Succession, a conflict over the duchy’s control, which involved various factions and external powers, including England and France. During his rule, John III sought to strengthen Brittany's independence and maintain its unique identity. He was known for his efforts to secure alliances and navigate the complex political landscape of medieval France. John III passed away in 1364, leaving a legacy of resilience in the face of external pressures.