While they were eventually expelled by Alan's grandson, Alan II, Duke of Brittany, the subsequent rulers of Brittany were weaker than Alan the Great.
Subsequent to the invasion of the Loire Viking fleet led by Rognvaldr in 919, he exiled himself and his son Alan, to England.
Brittany | Duke University | Duke Ellington | Duke | Duke of Wellington | Alan Moore | Prince William, Duke of Cambridge | Duke of York | Alan Lomax | Alan Alda | Duke of Norfolk | Alan Jackson | Alan Shearer | Duke of Edinburgh | Duke of Burgundy | Alan Turing | Alan Greenspan | Alan Autry | Prince Arthur, Duke of Connaught and Strathearn | George Villiers, 1st Duke of Buckingham | Prince Andrew, Duke of York | Alan Ayckbourn | Duke of Northumberland | Alfred, Duke of Saxe-Coburg and Gotha | Prince Richard, Duke of Gloucester | Prince Frederick, Duke of York and Albany | George Duke | Charles Lennox, 2nd Duke of Richmond | Alan Jay Lerner | Alan Ridout |
On 1 August 939, with the aid of Judicael (Berengar), count of Rennes, and Hugh I, count of Maine, his victory was made complete by defeating the Norse at Trans.
Alan II, Earl of Menteith married an unknown lady, by whom he had a daughter Mary II, Countess of Menteith.
Bertha of Blois, the daughter of Odo II of Blois, became Duchess Consort of Brittany through her marriage to Alan II, Duke of Brittany.
Francis I (in Breton Fransez I, in French François I) (Vannes/Gwened, 14 May 1414 – 18 July 1450, Château de l'Hermine/Kastell an Erminig), was Duke of Brittany, Count of Montfort and titular Earl of Richmond, from 1442 to his death.
Anne of Brittany was the last independent ruler of Brittany, inheriting the Duchy as a girl of twelve in 1488, and securing her inheritance was a crucial matter for both the House of Habsburg and the French Crown.
He sold all he possessed to the English, and his fief of Fougères to the Duke of Brittany.
Sometime after 1355, his son Sir John married Mary II, suo jure Countess of Menteith, the daughter of Alan II, Earl of Menteith.
Peter II (in Breton Pêr II, in French Pierre II) (1418–1457, Nantes/ Naoned), was Duke of Brittany, Count of Montfort and titular earl of Richmond, from 1450 to his death.