Barrois , old county, then duchy, on western border Lorraine , an area of the Holy Roman Empire , of which Barrois was long a fief or possession before being France was piecewise absorbed . The center and capital was the city later known as Bar-le-Duc in modern French Department Maas became known.
Due to its position between France and Germany, the duchy was marked by uncertain loyalty for many years. 951 passed the German Emperor Otto I. Frederick of Ardenne County Barrois ( ie the district of Bar), then a fief of the Duchy of Lorraine. When Frederick's great-great-grandson Renaud (Reynald) inherited the earldom, he founded the House of Bar. The Counts of Bar increased their wealth and became the most powerful vassals of the Dukes of Lorraine, with whom they fought endless battles, usually in the French ranks while the Dukes clung to the Germans . Count Henry III. Ally with Edward I. by England and the German king Adolf von Nassau against France. Defeated in battle against the French, Henry III. Forced in 1301 to the French King Philip IV for that part of the Barrois west of the Maas from which claimed he located in the Mouvance or feudal dependency of France and France from then on called the "Barrois mouvant".
In 1354 Robert of Bar assumed the title of Duke of Bar. 1420 married René of Anjou who had inherited the duchy, Isabella, heiress to the Duke of Lorraine, so that after his death (1431) Barrois and Lorraine were united. From then on, the Barrois shared the fate of Lorraine, which died in 1766 after the death of the former Polish king Stanisław Leszczyński It was granted in 1738 was attached to the French crown .