Battle of Trans-la-Forêt

The Battle of Trans-la-Fôret was fought on 1 August 939 between the occupying Norsemen and the Bretons, led by a joint army of Alan II, Hugh II of Maine, and Judicael Berengar.[1][2][3]

Battle of Trans-la-Fôret
Map commune FR insee code 35339.png
Location of Trans-la-Forêt within Brittany region
Date1 August 939
Result Decisive Breton victory
Commanders and leaders
Alan II
Judicael Berengar
Hugh II of Maine

Political landscapeEdit

Throughout the early 900's, the states of Brittany and West Francia were in a state of flux having both being invaded by the Norse:

  • In 931, the Norse assembled a army on the Loire river to attack the Franks. The occupied Bretons seized this opportunity and rebelled. The Norse appear to have been taken by surprise but a counterattack ensured Brittany was reconquered.
  • By 935, the Norse in Brittany became isolated after William Longsword of Normandy reconciled with the Franks and exiled Bretons started returning from Anglo-Saxon England. Alan Barbetorte returned to Brittany from Anglo-Saxon England between 936 and 938, and engaged the Norse. A Viking leader Incon was slain and Nantes recaptured in 937.
  • Receiving support from the Anglo-Saxon King Athelstan, the Bretons spread their rebellion throughout the peninsula and this brought them into direct confrontation with the Norse colonists.[4][5]

Through the course of three years, the campaign against the Norse reached a conclusion at Trans-la-Fôret.

Order of BattleEdit

On August 1, 939, a united Breton army lead by Alan II, a Breton count Judicael Berengar of Rennes and elements from a Frankish count Hugh II of Maine decisively attacked and defeated the Norse stronghold, bringing an end to the occupation.

The site of the battlefield is considered to be south of Mont St Michel over the river Couesnon within a kilometre from Trans-la-Fôret.[6]


The Breton victory at Trans-la-Forêt freed Brittany of Viking/Norse occupation and led to the re-establishment of the Breton State, not as a fully independent Kingdom but as a Sovereign Duchy under Alan II, Duke of Brittany, due to a new fealty owed to the Franks for helping remove the Norse.[7]

The occupation resulted in Brittany becoming more fortified on the seaward side by returning Breton lords.

Viking piracy continued to affect a previously vibrant maritime trade between the Bretons and their Welsh cousins, isolating the Bretons.

Armorican texts protected by monks for centuries were lost after this period.

The Breton capital was moved from Nantes to inland Rennes as it was regarded as more defensible. This would become a point of discord between the two cities.


  1. ^ Kim Hjardar, Vegard Vike.Vikings at War. Casemate Publishers & Book Distributors, LLC, 2016. p 334
  2. ^ Arthur Le Moyne de La Borderie, Barthélemy Pocquet. Première période. De l'an 995 après 1715-1789. Volume 2 de Histoire de Bretagne. J. Floch, 1972. p 397
  3. ^ Marcel Donet. Saint-Médard-sur-Ille: essai monographique. La Ville, 1985. p 215
  4. ^ Haywood, J. Northmen, the Viking Saga 793-1241 AD, Head of Zeus Publishing 2015
  5. ^ Cronenvet, P.N. Basileos Anglorum: a study of the life and reign of King Athelstan of England, 924-939, University of Massachusetts Amherst, Feb 2014
  6. ^ Price, N. The Vikings in Brittany, Society for Northern Research, University College, London, 1989
  7. ^ Henri-Georges Gaignard. Visages de Rance: flâneries à travers les pays malouin et dinannais. Fernand Lanore, 1983. p 100