John V, Duke of Brittany

John V (in French Jean V) (1339 – November 1, 1399), known as the Conqueror, was duke of Brittany and count of Montfort, from 1345 to his death. He was son of Duke John de Montfort, Duke of Brittany and Joanna of Flanders.

The first part of his rule was tainted by the Breton War of Succession, fought against his cousin Joanna of Dreux and her husband Charles of Blois. After his father's death, his mother took him to England to ask for the aid of Edward III. His mother was declared insane and imprisoned in Tickhill Castle in 1343. He was taken in to the King's household afterwards. In 1364, John V managed to win an important victory against the House of Blois in the battle of Auray, with the help of the English army. His rival Charles was killed in battle and Joanna forced to sign the Treaty Guérande on April 12, 1365. In the terms of the treaty, Joanna gave up her rights to Brittany and recognized John IV as sole master of the duchy. Surprisingly, John V declared himself a vassal to king Charles V of France, not to Edward III of England who helped him to become duke. Nevertheless, the French exerted pressure over Brittany and the local nobles and forced John V to exile between 1373 and 1379.

John V married three times:

1) princess Mary of England (1344–1362), daughter of Edward III of England and Philippa of Hainault;

2) in London in May 1366, Joan Holland (1350–1384), daughter of Thomas Holland, 1st Earl of Kent and

3) at Saillé-près-Guérande on October 2, 1386, princess Joanna of Navarre (1370–1437), daughter of Charles II of Navarre, the mother of his children:

• Jeanne of Brittany (Nantes, August 12, 1387 – December 7, 1388)
• a daughter (1388)
• John VI, Duke of Brittany (1389–1442)
• Marie of Brittany (Nantes, February 18, 1391 – December 18, 1446), Lady of La Guerche, married at the Château de l'Hermine on June 26, 1398 John I of Alençon
• Marguerite of Brittany (1392 – April 13, 1428), Lady of Guillac, married on June 26, 1407, Alain IX, Viscount of Rohan and Count of Porhoët (d. 1462)
• Arthur III, Duke of Brittany (Château de Succinio, August 24, 1393 – December 26, 1458, Château Nantes)
• Gilles of Brittany (1394 – July 19, 1412, Cosne-sur-Loire), Lord of Chantocé and Ingrande
• Richard of Brittany (1395 – June 2, 1438, Château de Clisson), Count of Benon, Étampes, and Mantes, married in 1423 Margaret d'Orléans, Countess of Vertus, daughter of Louis of Valois, Duke of Orléans
• Blanche of Brittany (1397 – aft. 1419), married at Nantes on June 26, 1407 John IV, Count of Armagnac

Preceded by: John IV disputed with Charles	Duke of Brittany 1345–1399	Succeeded by: John VI
	Count of Montfort 1345–1389
Preceded by: John of Gaunt surrendered and re-created	Earl of Richmond 1372 - 1399	Succeeded by: Vacant, next held by John of Lancaster