The Battle of Brissarthe was fought on 2 July 866), between the Franks and a joint Breton-Viking army near Brissarthe, Neustria. It was marked by the death of Robert the Strong, the Neustrian margrave, and Ranulf I, the duke of Aquitaine. In 866, Salomon, Duke of Brittany, allied with Hastein (Hasting), a Danish chieftain, for an expedition into Anjou, Maine, and Touraine. In the course of the campaign, Le Mans was sacked. Robert, commander of the afflicted regions, assembled a large army to expel them. He was joined by Ranulf of the region of Poitou and Gauzfrid and Hervé of Maine.