Battle of Ballon The Battle of Ballon took place on 22 November 845 between the forces of Charles the Bald , king of West Francia , and Nominoë Duke of Brittany . Nominoë was appropriating border territory and opposing Charles ' attempt to impose Frankish authority . Nominoë defeated Charles , initiating a period of Breton expansion and consolidation of power . Background . Following the death of Louis the Pious , Nominoë initially supported Charles the Bald in the dispute between him and his brothers over control of Frankish territory . However , when Count Ricuin of Nantes was killed at the Battle of Fontenoy , Charles refused to accept Lambert II as his successor , since Lambert ' s father , Lambert I , had fought against Charles . Charles replaced him with his supporter Renaud , Count of Herbauge . While Nominoë was ill , Renaud attacked Breton territory , but was killed in battle by the Bretons led by Erispoe , Nominoë ' s son , in alliance with Lambert . This allowed Lambert to occupy Nantes with the support of Nominoë . Recovered from his illness , Nominoë hoped to take advantage of the disorder to expand into Frankish territory . On campaign in Aquitaine , Charles was initially unable to respond to the incursions . Learning of Charles ' s difficult military position in Toulouse , Nominoë continued his offensive , raiding Maine . In 845 , Charles concluded a peace with Pepin II of Aquitaine and was reconciled with Lambert II of Nantes , freeing him to deal with the threat from Nominoë . In November , he had intended to participate in a religious festival in Tours , but he decided to strike against Nominoë instead , having heard that a faction of discontented Bretons would defect to him if he hastened to their aid . The battle . Charles quickly assembled an army of around 3 , 000 men . Nominoë ' s men were probably much fewer in number , comprising mostly a highly mobile light cavalry . Nominoë lured the king into marshland at the confluence of the Oust and the Aff between Redon and Bains - sur - Oust , near Ballon Abbey - hence the name of the battle . The Bretons were then able to exploit their knowledge of this treacherous wetland territory . Details of the events of the actual battle are sketchy . Reports simply state that Charles was defeated . According to the Annals of Saint - Bertin : According to First Annales de Fontenelle : Aftermath and significance . Following his defeat , rumors circulated that Charles had been killed , forcing him to make a quick public appearance in Maine . While there he rebuilt his army , and headed back towards Brittany late in 846 . There he concluded a treaty with Nominoë , though the exact content of the agreement is unknown . Despite this a " cold war " persisted , and Breton raids continued into Frankish territory at Christmas of that year . Nevertheless the agreement remained unbroken until 849 . This relatively minor battle is often confused with the much more decisive Battle of Jengland won by Nominoë ' s son Erispoe against Charles in 851 . This confusion dates to Arthur de la Borderie ' s 1894 " History of Brittany " and has been repeated many times since . However , it is to the battle of Ballon that some date the birth of a unified and independent Brittany , behind a single sovereign : Nominoë . The expansionist policy of Nominoë , by the conquest of the former Marches of Brittany , a Frankish buffer zone , was continued by Erispoe , who consolidated the borders of medieval Brittany . In the twentieth century the battle was given emblematic status by Breton nationalists . In 1952 the battle was commemorated by the nationalist group Koun Breizh , who funded the erection of a statue of Nominoë by the artist Raffig Tullou in Bains - sur - Oust , near the site of the victory . Another nationalist group , " Bretagne 845 " , founded in 1982 , was named from the date of the battle . It merged with Koun Breizh in 1994 .