Mirebeau is a commune in the Vienne department, in the region of Nouvelle-Aquitaine, western France. Fulk Nerra, Count of Anjou conq…Mirebeau is a commune in the Vienne department, in the region of Nouvelle-Aquitaine, western France. Fulk Nerra, Count of Anjou conquered Mirebeau and built a castle there. His son, Geoffrey of Anjou, defeated William VI, Duke of Aquitaine and Count of Poitou at the battle of Moncontour on September 20, 1033, and from that date Mirebeau belonged to the county of Anjou until 1790, and the replacement of the old provinces by departements during the French Revolution.