Captal de Buch (later Buché) was an archaic feudal title in Gascony, captal from Latin capitalis "prime, chief" in the formula capitales domini or "principal lords." As an actual title the word "captal" was used only by the seigneurs of Trene, Puychagut, Epernon and Buch.
When Pierre, the seigneur of Grailly (ca 1285 - 1356) married Asalide (the captaline de Buch), the heiress of Pierre-Amanieu de Bordeaux, captal de Buch, in 1307, the title passed into the Grailly family, a line of fighting seigneurs with origins in Savoy.
The most famous of the Captals de Buch was Pierre's grandson, Jean III de Grailly, captal de Buch (1343 - 1377), a cousin of the Count of Foix who was a military leader in the Hundred Years' War, praised by the chronicler Jean Froissart as an ideal of chivalry.
Attached to the English side in the conflict, he was made Count of Bigorre by Edward III of England. He played a decisive role as a cavalry leader under Edward, the Black Prince in the Battle of Poitiers (1356). He defected to the French side and was made lord of Nemours by Charles V of France, but re-established his loyalty to the English and was rewarded by being made the Constable of Aquitaine.
Froissart gives an account of the Captal de Buch's chivalry and courage at the time of the peasant uprising in 1358 called the Jacquerie (see link).
In 1372, he was captured by the French near Soubise and was imprisoned in Paris until his death. Since he left no heirs, his uncle, Archambaud, count of Foix and of Bigorre took the title Captal de Buch, which passed to his descendents the Counts of Foix.
The most famous of the CaptalsdeBuch was Pierre's grandson, Jean III deGrailly, captaldeBuch (1343 - 1377), a cousin of the Count of Foix who was a military leader in the Hundred Years' War, praised by the chronicler Jean Froissart as an ideal of chivalry.
Genealogy of the seigneurs deGrailly, captalsdeBuch
Charles III.'s daughter, Beatrix, brought the duchy to her husband Jacques de Bourbon, count of La Marche, and by the marriage of their daughter, Eleanor, to Bernard of Armagnac, count of Pardiac, it passed to the house of Armagnac.
The duchy then returned to the royal domain, and was detached from it successively for Giuliano de Medici and his wife Philiberta of Savoy in 1515, for Louise of Savoy in 1524, and for Philip of Savoy, count of Genevois, in 1528.
Anne Genevieve de Bourbon-Conde, the celebrated duchesse de Longueville; and when her husband died in 1659, leaving her childless, the rest of her life was mainly spent in contesting her inheritance with her stepmother.