John IV, Duke of Brittany Duke of Brittany (1294–1345) Parents Yolande of Dreux Arthur II, Duke of Brittany Children John V, Duke of Brittany Joan of Brittany, Baroness of Drayton Siblings John III, Duke of Brittany Alice of Brittany Beatrice of Brittany Guy of Penthièvre Marie de Montfort Jeanne de Dreux-Bretagne, Dame de Nogent-le-Rotrou Blanche de Montfort Pierre de Bretagne Partners Joanna of Flanders
