Joan of Valois, Countess of Hainaut

Joan of Valois (c. 1294–1352) stood where the French and English crowns met. Daughter of Charles of Valois and sister of Philip VI of France, she married William I of Avesnes, Count of Hainaut, Holland and Zeeland, and governed Hainaut as regent whenever he was away.

Her daughter Philippa married Edward III of England, which made Joan mother-in-law to one king and sister to the other. After William died in 1337 she took the veil at Fontenelle Abbey, but kept her chancellery and staff.

In 1340, after Edward beat Philip at Sluys and besieged Tournai without money to carry on, Pope Benedict XII asked her to mediate. She begged her brother for peace, then went to Edward's tent and begged him too; on 23 September the two kings agreed a truce without loss of face. In 1345 she mediated a quarrel in Tournai. She died at Fontenelle in 1352.