Two rival claimants to the Duchy of Brittany, John of Montfort and Charles of Blois, competed for Vannes throughout this civil war from 1341 to 1365.

Saved by an appeal of Pope Clement VI, Vannes remained in the hands of its own rulers, but ultimately resided under English control from September 1343 till the end of the war in 1365.

In the beginning of the 14th century, the Sovereign Duchy of Brittany was culturally close to Celtic portions of the British Isles and this made it part of a sphere of economic influence with England, to which it supplied salt.

He captured the Ducal home in Limoges and moved to Nantes, where he convened the nobility of Brittany for recognition as the Duke.

This attempt failed – the Breton Barons did not come for fear of reprisals, so on 1 June he embarked on a tour throughout the Duchy to ensure control of strongholds.

At night, Artois, accompanied by William Montagu, Earl of Salisbury, lit two fires in front of two of Vannes gates and attracted the city garrison there.

During that time, a small group led by Walter Manny and the Count of Quenfort[note 2] attacked a section of the wall abandoned by the defenders.

She remained there for five days then returned to Hennebont with Walter Manny, leaving Robert d'Artois in charge of the Anglo-Breton garrison.

Clisson raised about 12,600 men in addition to those of Robert II of Beaumanoir, Marshal of Brittany, and headed towards Vannes.

[3] He could not prevent the loss of Vannes — troops from Blois entered the breaches that had occurred from the previous siege, that had not been repaired in time.

At the same time, Louis of Spain and Antonio Doria, admirals of France at the head of one hundred galleys and thirty ships, attacked all vessels carrying arms and supplies to the English.

After losing several ships, Edward III, dispersed his fleet in order to save it; a portion was sent to Brest and another to Hennebont.

Two legates of Pope Clement VI intervened, avoiding confrontation between the two armies: they obtained a three-year truce signed in Malestroit on 19 January 1343.

[5] In accordance with the stipulations of the Treaty of Malestroit, signed in January 1343, Vannes was temporarily handed over to the Cardinal Legates of pope Clement VI, who installed governors.

[6] The citizens of Vannes as well as the local clergy were however loyal to John de Montfort and drove out the Papal agents a few months after the signing of the treaty.

Due to the perceived small amount of that ransom, Philip IV of France and his counsellors suspected Clisson of having intrigued with Edward III of England.

[8] This hasty execution shocked the nobility, his guilt of treason not having been publicly demonstrated at the time, since the decision had been taken by the King,[note 3] without process.

This saga ended when some warships of the King of France seized the ships of Jeanne de Belleville, who managed to escape with her two sons on a lifeboat.