Fulk III Nerra, Count of Anjou, approximately 970-1040

Fulk III, the Black (c. 970–1040; Old French: Foulque Nerra) was an early Count of Anjou celebrated as one of the first great builders of medieval castles. It is estimated Fulk constructed approximately 100 castles as well as abbeys throughout the Loire Valley in what is now France. He fought successive wars with neighbors in Brittany, Blois, Poitou and Aquitaine and made four pilgrimages to Jerusalem during the course of his life. He had two wives and three children. Fulk was a natural horseman and fearsome warrior with a keen sense of military strategy that bested most of his opponents. He was allied with the goals and aims of the Capetians against the dissipated Carolingians of his era. With his county seat at Angers, Fulk's bitter enemy was Odo II of Blois, his neighbor 128 km east along the Loire river, at Tours. The two men traded towns, followers and insults throughout their lives. Fulk finished his first castle at Langeais, 104 km east of Angers, on the banks of the Loire. Like many of his constructions, it began as a wooden tower, and was eventually replaced with a stone structure, fortified with exterior walls, and equipped with a thick-walled tower called a donjon in French (source of the English word "dungeon", which, however, implies a cellar rather than a tower). He built it in the territory of Odo I, Count of Blois, and they fought a battle over it in 994. But Odo I died of a sudden illness, and his son and successor, Odo II, did not manage to evict Fulk. Fulk continued building more towers in a slow encirclement of Tours: Montbazon, Montrésor, Mirebeau, Montrichard, Loches, and even the tower of Montboyau, erected just across the Loire from Tours in 1016. He also fortified the castles at Angers, Amboise, Chateau-Gontier, Chinon, Mayenne and Semblançay, among many others. "The construction of castles for the purpose of extending a ruler's power was part of Fulk Nerra's strategy," wrote Peter Fraser Purton, in A History of Medieval Siege, c. 450–1220. Fulk was also a devout Christian who built, enlarged or endowed several abbeys and monasteries, such as the Abbey of Beaulieu-lès-Loches, Saint-Florent-le-Vieil, Saint-Aubin, and a convent, Notre Dame de la Charité, at Ronceray in Angers. Although he never learned to write, he endowed a school with revenue to provide poor students with an education. Fulk also undertook four pilgrimages to Jerusalem.