Olivier IV de Clisson (c. 1300–1343), was a Breton Marche Lord and knight who became embroiled in the intrigue of Vannes and was subsequently executed by the King of France for perceived treason.

Jeanne, a recent widow herself of the lord of Chateaubriant, controlled areas in Poitou just south of the Breton border from Beauvoir-sur-Mer in the west to Cheaumur in the southeast of Clisson.

Combining these assets would make Jeanne and Olivier the seigneurial power (senior Lord of an area) in the border region of Brittany.

It was this Amaury who then concluded an agreement on 10 March 1342, in Westminster with Edward, the King of England and returned to Brittany with 6000 archers saving the de Montforts sieged at Hennebont.

[5] In November 1342 Olivier IV, raised about 12,600 men, in addition to those of Lord Beaumanoir, Marshal of Brittany, and headed towards the captured city of Vannes.

Under the perceived safe conditions of this truce, Olivier and fifteen other Breton lords were invited to a tournament on French soil, where he was subsequently arrested and taken to Paris.

And then from there his corpse was drawn to the gibbet of Paris and there hanged on the highest level; and his head was sent to Nantes in Brittany to be put on a lance over the Sauvetout gate as a warning to others.

She managed to evade arrest as she was being protected by Olivier's eldest son Jean, Guilaume Berard, her squire and valet, Guionnet de Fay and Guillaume Denart.