The Duchy of Brittany (Breton: Dugelezh Breizh, [dyˈɡɛːlɛs ˈbrɛjs]; French: Duché de Bretagne) was a medieval feudal state that existed between approximately 939[a] and 1547.

Her sons Francis III, Duke of Brittany and then Henry II of France would in any case have created a personal union on the death of their father.

[3] Between the late 4th and the early 7th centuries, many of these Britonnes migrated to the Armorican peninsula, blending with the local people to form the later Britons,[4] who eventually became the Bretons.

[9] The Carolingians tried to create a unitary administration around the centres of Rennes, Nantes, and Vannes using the local rulers, but the kings of Brittany's hold on the region remained tenuous.

Alan I successfully defeated one wave of Vikings around 900, expanding the kingdom to include not only the Breton territories of Léon, Domnonée, Cornouaille, and the Vannetais, but also the Frankish counties of Rennes, Nantes, Coutances, and Avranches, as well as the western parts of Poitou and Anjou.

[25] Alan's duchy was smaller than the previous Kingdom of Brittany, as, despite gaining Magues and Tiffauges in the south, the dukes no longer ruled over the regions of Cotentin, Avranchin, and Mayenne.

[7] Over the coming decades, a network of powerful local lords emerged across Brittany, occupying motte and bailey castles and owing a loose feudal loyalty to the duke.

Two of Alan II's illegitimate sons, Hoël and Guerich, attempted to act as Counts of Nantes and preserve their claim to duchy but were eventually unsuccessful.

The death of Geoffrey I, in 1008, allowed Richard II to intervene directly in Brittany during the minority of his nephew, Alan III, against rebellious counts who attempted to take advantage of the youthful duke.

Alan III countered the instability by reinforcing the power of the Norman ducal house providing Robert I's two youngest brothers with land and title.

[32] A rival faction in the guardianship of Normandy emerged, one that would intervene in Brittany, suppressing Alan III's heir, Conan II, from claiming his inheritance.

In 1065, before his invasion of Anglo-Saxon England, William of Normandy warned his rivals in Brittany and Anjou to abstain from any attacks on his duchy, on the grounds that his mission bore the papal banner.

[38] The barons in Brittany did not feel that they were in any way vassals of the duke, owing him service in exchange for their lands, and only attended the ducal courts when they felt it was in their own interests to do so.

Eustace's death provided an opportunity for Matilda's son, Henry FitzEmpress, to land an invasion army in England and press for his mother's claims.

Throughout these years, Constance advised her son Arthur towards a French alliance, pursuing the policy of her late husband Geoffrey II, despite his designation as Richard I's heir.

In 1214, King John sent an expedition into France, in part to establish Eleanor as his puppet duchess, but after his defeat also recognized Alix and Peter as rulers of the Duchy.

The House of Montfort emerged victorious with substantial help from English allies[h] Under the terms of their surrender, Joan was allowed to keep Penthièvre and retained the title Duchess of Brittany for life.

John IV, Duke of Brittany ruled with difficulty after the Breton civil war, and was forced into exile in England for a second time in 1373 where he lived in the court of Edward III.

The Houses of Penthièvre and Montfort were united in the sense of their opposition to the attempted annexation of Brittany by Charles V of France as a consequence of this Breton civil war.

When the Breton nobles rebelled against this proposed unification, John IV was able to return from England, assisted once again by a strong army including his English ally, and was able to re-establish his rule.

The reign of Francis II was notable in many respects including two wars against Charles VIII of France, both of which were lost, the establishment of the Parlement of Rennes, and the death of all of his children save for his daughter Anne of Brittany.

[citation needed] Francis II worked to seek a husband for Anne who would be strong enough to defend Brittany from further influence from the French Crown.

The Duchy was inherited by his daughter, Anne, but King Charles VIII of France, determined to bring the territory under royal control, had her marriage annulled and then forced her to marry him in a series of actions that were acknowledged by the Pope.

Louis XIV's actions with regard to the Ducal title also underscored the fact that the Spanish or cadet branch of the House of Bourbon had relinquished all French claims and inheritance rights as a condition of gaining the crown of Spain under the Treaty of Utrecht.

Shortly before the French Revolution the leaders of the Parlement of Rennes issued Remonstrances to Louis XVI, in part to remind the King of his duties as Duke and to preserve the privileges of the Breton people under the Treaty of Union.

[42] A reference is made by the chronicler Jordanes to a commander named Riothamus – the Celtic for "supreme leader" – fighting in the region on behalf of the Roman emperor around 470 but little other evidence exists for this period.

[49] The Duchy that formed in the 10th and the 11th centuries was a feudal society, with laws and customs run through a hierarchy of Breton lords, from the numerous holders of local castles through to the handful of counts and the Duke in the urban centres.

[51] The aristocracy in Breton were, as historians Galliou and Jones describe, "conservative and tenancious" in their outlook, but heavily influenced by French society and culture, which sometimes produced tensions with older, more local traditions and customs.

While Henry II of France held all rights as Duke of Brittany he was neither frequently present in the Duchy nor entirely inclined to preserve the independent actions of its parliament.

It was disbanded by Louis XIV but the Parlement voted to ignore the King's order of dissolution upon the claim it alone had the authority to dissolve this legislative and judicial body.