However, the Brittons quickly rallied their troops and took the complacent Franks by surprise shortly thereafter at the Battle of Blain, inflicting a serious defeat resulting in the death of Count Renaud.
Erispoe met Charles in Angers (possibly in secret[2]) in the days following the battle and concluded a peace treaty in return for being invested with the counties of Rennes and Nantes.
[5] According to the Annales Bertiniani, at Louviers in February 856 Erispoe's daughter (unnamed in the sources) was betrothed to Charles's young son, Louis the Stammerer, who was granted the ducatus Cenomannicus as subking of Neustria with Le Mans as his capital.
[6] With the consent of the Frankish magnates, Louis received the regnum Neustriae from his father: Karlus rex cum Respogio Brittone paciscens, filiam eius filio suo Ludoico despondet, dato illi ducatu Cenomannico usque ad viam quae a Lotitia Parisiorum Cesaredunum Turonum ducit.
King Charles, making peace with Erispoe of Brittany, the daughter of whom was betrothed to his son Louis, gave the duchy of Maine as far as the road from Paris to Tours as duke.
Erispoe was at peace with Charles for the whole of his reign after Jengland and he governed as a typical Carolingian regional official might, with the added dignity of a consors regni (royal consort).
[10] In November 857 he was assassinated at the altar of a church, which was then considered a place of asylum, by his cousin and successor Salomon, aided by an obscure Almarchus (Almarus).