The House of Dreux was a

cadet branch In history and heraldry, a cadet branch consists of the male-line descendants of a monarch's or patriarch's younger sons ( cadets). In the ruling dynasties and noble families of much of Europe and Asia, the family's major assets— realm, tit ...

of the Capetian dynasty. It was founded by Robert I, Count of Dreux, a son of Louis VI of France, who was given the County of Dreux as his appanage. The Counts of Dreux were relatively minor nobles in France. The senior comital line became extinct in 1345. In 1212 the French king needed an obedient vassal to marry Alix, Duchess of Brittany and turned to his cousin

Peter Peter may refer to: People * List of people named Peter, a list of people and fictional characters with the given name * Peter (given name) ** Saint Peter (died 60s), apostle of Jesus, leader of the early Christian Church * Peter (surname), a sur ...

, a younger son of the Count of Dreux. Peter's marriage to the heiress of Brittany placed the House of Dreux in one of the most important fiefs of France. Brittany became a lay peerage of the France in 1297 and was formally recognised as a duchy (rather than a county) by the French court. The Dreux rulers of Brittany descending from Peter used a canton ermine to mark them as cadets of the House of Dreux. Sometime in 1316, John III, Duke of Brittany adopted the plain ermine as the arms of the Duchy of Brittany. At the death of John III in 1341, the succession to the duchy was contested by the duke's niece, Joan of Penthièvre, daughter of his full-brother, and John of Montfort, the duke's younger half-brother. Traditionally, females had been able to succeed as duchesses, but this practice was not consistent with most apanages granted by the French crown, which usually preferred male-only succession. Joan had married

Charles of Blois Charles of Blois-Châtillon (131929 September 1364), nicknamed "the Saint", was the legalist Duke of Brittany from 1341 until his death, via his marriage to Joan, Duchess of Brittany and Countess of Penthièvre, holding the title against the c ...

, a nephew of King Philip VI, who supported their cause.

Edward III of England Edward III (13 November 1312 – 21 June 1377), also known as Edward of Windsor before his accession, was King of England and Lord of Ireland from January 1327 until his death in 1377. He is noted for his military success and for restoring ...

, meanwhile, supported the Montforts. John died in 1345 from an illness caught while besieging Quimper. His young children were placed into English custody. John's son,

John John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Secon ...

was allowed to return to Brittany in 1362. Meanwhile, Charles was captured by the English in 1347 and imprisoned until 1356. Charles ultimately died at the

Battle of Auray The Battle of Auray took place on 29 September 1364 at the Breton-French town of Auray. This battle was the decisive confrontation of the Breton War of Succession, a part of the Hundred Years' War. In the battle, which began as a siege, a Bre ...

in 1364, fighting the forces of the younger John. In the Treaty of Guérande, which ended the

War of the Breton Succession The War of the Breton Succession (, ) was a conflict between the Counts of Blois and the Montforts of Brittany for control of the Sovereign Duchy of Brittany, then a fief of the Kingdom of France. It was fought between 1341 and 12 April 1 ...

, the Duchy of Brittany was made hereditary in the males of the Montfort line, at the termination of which it was to pass to the males of Blois-Penthièvre. In 1420 the Penthièvre family imprisoned the duke in a failed attempt to regain Brittany. When the last male Montfort duke,

Francis II of Brittany Francis II ( Breton: ''Frañsez II'', French: ''François II'') (23 June 1433 – 9 September 1488) was Duke of Brittany from 1458 to his death. He was the grandson of John IV, Duke of Brittany. A recurring theme in Francis' life would be h ...

, died, the duchy passed to his daughter, Anne of Brittany.

Arms

{{Multiple image , align = center , direction = , background color = , header_background = , header_align = , header = Arms of the House of Dreux , width = 140 , image1 = Arms of Robert de Dreux.svg , caption1 = Count of Dreux , image2 = Arms of Pierre Mauclerc.svg , caption2 = Duke of Brittany
Breton coat of arms from 1212 to 1316 , image3 = Arms of Jean III de Bretagne.svg , caption3 = Duke of Brittany
Breton coat of arms after 1316. These are still in use today by the government of Brittany. , image4 = Arms of Guy de Penthièvre.svg , caption4 = Count of Penthièvre
Arms of Guy, Count of Penthièvre son of Arthur II, Duke of Brittany Dreux