Vikings in Brittany

This would eventually lead to the downfall of the short-lived Kingdom of Brittany and a two-decade long occupation by the Norse only for this to be finally broken with support arriving from surprising sources.

[2] In June 843 the Norse attacked and sacked the Frankish-controlled city of Nantes as it was bereft of defenders due to the Battle of Messac.

[3][4][better source needed] The Breton army under Nominoe in 845 defeated the forces of Charles the Bald, King of West Francia, at the Battle of Ballon, in the eastern part of Brittany near Redon and the Frankish border.

Nominoe gained control over Rennes and Nantes, which had previously formed part of a Frankish border zone known as the Breton March.

[5][better source needed] The Frankish army was again defeated in 851 at the Battle of Jengland by the Bretons under Erispoe and control over Rennes, Nantes and the Pays de Retz was secured.

Under Salomon, King of Brittany, Hastein's Norse in 865 united with the Bretons again to defeat a Frankish army at the Battle of Brissarthe, near modern-day Le Mans.

Peace lasted until the spring of 872 when the Norse fleet sailed up the Maine and occupied Angers, which led to a siege by Charles the Bald.

"[11] In 919 the Franks ceded Nantes to Rognvaldr, who renamed it Namsborg, made peace and agreed to convert to Christianity for being allowed to keep Upper Brittany.

[14] By 935 Incon was isolated after William Longsword of Normandy reconciled with the Franks and exiled Bretons started returning from Britain.

The Battle of Trans-la-Fôret was fought on 1 August 939 between the occupying Norse and the Bretons, led by a joint army of Alan II of Brittany, Judicael Berengar of Brittany and the Frank Hugh II, Count of Maine, who decisively attacked and defeated the Norse stronghold, bringing an end to the occupation.

A Norse saga attributed to Snorri Sturluson mentions that sporadic attacks continued into 1015 when the Breton town of Guerande was destroyed.