Joan of Penthièvre was a noblewoman born in 1326, known for her connection to the royal family of France. She was the daughter of Charles of Blois and Margaret of Penthièvre, and her lineage linked her to the ducal house of Brittany. Joan's life was marked by the political struggles of her time, particularly the conflict between the houses of Blois and Montfort over the control of Brittany. In 1347, Joan married John IV of Montfort, which further complicated the ongoing power struggle in Brittany. Her marriage was significant in the context of the Hundred Years' War, as it aligned her with the Montfort faction. Joan's legacy is often overshadowed by the more famous figures of her time, but she played a crucial role in the dynastic politics of medieval France.