The greatest influence on the later Duchy, however, was the formation of a unitary Brittany kingdom in the 9th century. In 831 Louis the Pious appointed Nominoe, the Count of Vannes, ruler of the Bretons, imperial "missus", at Ingelheim in 831. After the death of Louis in 840, Nominoe rose to challenge the new emperor, Charles the Bald, emboldened in part by new Viking raids on the empire. Charles the Bald created the Marches of Neustria to defend Western Francia from the Bretons and the Vikings. Erispoe fought Charles the Bald, who felt that a quick attack would successfully challenge the new Breton leader. Erispoe won a victory at the Battle of Jengland and, under their Treaty of Angers in 851, Brittany's independence was secured.