The Battle of Trans-la-Fôret was fought on August 1, 939 between the occupying Vikings and the Bretons, led by the joint armies of Alan II, Count Hugh II of Maine, and Judicael Berengar. The Bretons prevailed; their victory at Trans-la-Forêt freed Brittany of Viking occupation, and led to the establishment of the Duchy of Brittany under Alan II, Duke of Brittany