Mathuedoï I, Count of Poher

Mathuedoï I (circa 875 - 930) was a Count of Poher. He was the son-in-law of Alan I, King of Brittany, known as Alan the Great through his marriage to Hawise of Vannes. He obtained his countship at Alan's death circa 907. He is listed in several ecclesiastical records at Redon Abbey.

At Alan I's death the rule of Brittany became fractured even as the region faced Viking invasions. Mathuedoï and his cousin Gourmaelon, the Count of Cornouailles, stood in line to succeed Alan I as ruler of Brittany. Mathuedoï renounced his claim as Viking invasions of Brittany increased. Subsequent to the invasion of the Loire Viking fleet led by Rognvaldr in 919, he exiled himself and his son Alan to England.

According to the Chronicle of Nantes:

While Mathuedoï would remain in England, his son Alan returned to Brittany about 15 years later, and with Athelstan's assistance would expel the Vikings.

...
Wikipedia