history. According to Breton king-lists, Riotham survived and reigned as Prince of Domnonia until his death sometime between 500 and 520, though this may have been a different person. Middle Ages The Kingdom of Brittany At the beginning of the medieval era, Brittany was divided among three kingdoms, Domnonea, Cornouaille and Broërec. These realms eventually merged into a single state during the 9th century. The unification of Brittany was carried out by Nominoe, king between 845 and 851 and considered as the Breton Pater Patriae. His son Erispoe secured the independence of the new kingdom of Brittany and won the Battle of Jengland against Charles the Bald. The Bretons won another war in 867, and the kingdom reached then its maximum extent: It received parts of Normandy, Maine and Anjou and the Channel Islands. Viking occupation Brittany was heavily attacked by the Vikings at the beginning of the 10th century. The kingdom lost its eastern territories, including Normandy and Anjou, and the county of Nantes was given to Fulk I of Anjou in 909. However, Nantes was seized by the Vikings in 914. At this time Brittany was also called Lydwiccum. The Duchy of Brittany Nantes was eventually liberated by Alan II of Brittany in 937 with the support of his godbrother King Æthelstan of England. Alan II totally expelled the Vikings from Brittany and recreated a strong Breton state. For aiding in removing the problem, Alan paid homage to Louis IV of France (who was Æthelstan's nephew and had returned from England in the same year as Alan II) and thus Brittany ceased to be a kingdom and became a duchy. Norman allies Several Breton lords helped William the Conqueror to invade England and received large estates there (e.g. William's double-second cousin Alan Rufus and the latter's brother Brian of Brittany). Some of these lords were powerful rivals. Internal disputes Medieval Brittany was far from being a united nation. The French king maintained envoys in Brittany, alliances contracted by local lords often overlapped and there was no specific Breton unity. For example, Brittany replaced Latin with French as its official language in the 13th century, 300 years before France did so, and the Breton language didn't have formal status. The foreign policy of the Duchy changed many times; the Dukes were usually independent, but they often contracted alliances with England or France depending on who was threatening them at