The hermine ("stoat") is the symbol of Brittany... When they came in Brittany, the dukes didn't have a proper castle in the city of Vannes. They were welcomed in Suscinio castle, in the Rhuys' peninsula.
It was the duke Jean IV, who built the Stoat castle (château de l'Hermine) and raised the city's surrounding walls; he bought a mill and the étang des Lices ("Tilt Yard's pond") for that, in 1380.
Bertrand d'Argentré described that castle in 1582: "It's a small building for a prince, which is made of a single main building and several turrets and two big towers."
Surrounding the castle, we had moats filled with water. To the North, we found the farmyard, with buildings where soldiers and horses lived. Nearby, the tilt yard. The legend said here, in 1381, 5 Bretons defeated 5 Englishmen during a tournament...
But after centuries, the old fortress was abandoned, and in the reign of Louis XIV, in 1697, they demolished it and replaced it by the current castle, raised in the 18th century.