The Dukes of Boulogne were noble titles in the historical region of Boulogne-sur-Mer, located in northern France. This title was held by various members of the French nobility from the 10th century until the 13th century. The dukes played a significant role in the feudal system, managing lands and providing military support to the crown. The title of Duke of Boulogne was often associated with the Counts of Boulogne, who were influential in regional politics and warfare. The dukes contributed to the development of the area, including its fortifications and trade routes, which were vital for economic growth during the medieval period.