Medieval County in Gascony in southwestern France, now mainly in, and forming much of, the Department of the Gers.
The original County was much smaller, just the west of the department, and was formed c.960 for the younger son of Count William of Fezensac, himself a younger son of Duke Garcia of Gascony. In 1140 the Count of Armagnac acquired the larger county of Fezensac to the east, so that from then on Armagnac extended from the River Adour to the River Gers. At the same time the city of Auch became the capital of the County, though in the city itself the Count had to share power with the Archbishop.
The orignal Counts, descended from the Dukes of Gascony, whom they sought but failed to succeed in the 1040s, died out in the male line in 1215, and were succeeded by the Vicomtes of Lomagne, a territory north of Auch. The Counts later gained lands outside of the old Duchy of Gascony when they acquired Rodez in the Rouergue in 1306.
The Counts were vassals of the Duke of Aquitaine for their Gascon lands, but threw off their allegiance to the English King in the Hundred Years’ War, and became some of the fiercest partisans of the French King and bitterest opponents of the Dukes of Burgundy. Count Bernard VII, who was Constable of France 1415-8, married his daughter to the son of that Duke of Orleans who had been murdered by Burgundians in 1407 and was himself murdered by them in 1418.
The following year his followers took their revenge on the Duke of Burgundy. Little wonder then that the two main factions in France at this time were called Armagnacs and Burgundians. (Armagnac came to mean, in eastern France and beyond, the wandering bands of murdering, plundering soldiers that lingered through the later years of the war and for some time after. An example of its use for French mercenary troops was in the Swiss wars of the 1440s).
The Counts did not long survive the French King’s final triumph over the English. For one thing, Louis XI, King from 1461, determinedly pursued powerful princes, at least when it was reasonably safe to do so. Amongst those he destroyed was the son of his former tutor, the powerful Armagnac cadet, the Duke of Nemours, who was executed in 1477. The head of the family, Count John V, endangered himself by his incestuous relationship and marriage with his sister. He was deprived of the County in 1460, later partially restored, but killed in 1473. His brother, Charles, was restored as Count in 1484, but fourteen years in jail had made him witless.
When he died in 1497, the County was granted to his sister’s grandson, Charles of Alençon. After his death in 1525, King Francis I gave it to his sister, Charles’s widow, and her second husband, the titular King of Navarre. Eventually their grandson inherited, and in 1589 became King Henry IV of France; in 1607 Armagnac was merged with the royal lands and became part of the province of Guyenne & Gascony.