John IV, Duke of Brittany

Coat of Arms of the Dukes of Brittany, and of the region Brittany

John IV of Montfort (in Breton Yann Moñforzh, in French Jean de Montfort) (1295 – 16 September 1345^{[citation needed]}, Château d'Hennebon), was duke of Brittany, from 1341 to his death. He was son of Duke Arthur II and Yolande de Dreux, countess of Montfort, his second wife.

In 1322 he succeeded his mother as count of Montfort, and in 1329, he married Joanna of Flanders at Chartres. They had two children:

• John V, Duke of Brittany (1339–1399)
• Joan of Brittany, Baroness of Drayton (1341 – aft. 20 October 1399), married before 21 October 1385 Ralph Basset, 4th Baron Basset de Drayton

Breton War of Succession

When his half-brother, duke John III, died with no male heirs in 1341, John IV decided to contest the rights of his niece, Joanna of Penthièvre, and her husband, Charles of Blois, to the duchy of Brittany. This led to the Breton War of Succession part of the Hundred Years' War. His patron in this quest was king Edward III of England.

See also

• Dukes of Brittany family tree

References

Regnal titles
Preceded by Yolande	Count of Montfort 1322–1345	Succeeded by John V
Preceded by John III	Duke of Brittany disputed with Joanna and Charles 1341–1345
Peerage of England
Preceded by John III of Dreux	Earl of Richmond 1341–1342	Succeeded by John of Gaunt