Louis VIII

Unusually for a Capetian, Louis VIII won his military reputation before ever wearing the crown. Born in 1187 to Philip II Augustus and Isabella of Hainaut — through whom the dynasty claimed a strain of Carolingian descent — he was the first heir in generations not crowned during his father's lifetime, so secure had the succession become. In 1200 he married Blanche of Castile, daughter of Alfonso VIII of Castile and Eleanor of England, and thus a granddaughter of Henry II Plantagenet and Eleanor of Aquitaine; the marriage was meant to seal peace between the Capetian and Plantagenet houses.

As crown prince, Louis defended the kingdom's western approaches, defeating King John of England's forces at La Roche-aux-Moines in 1214, the companion victory to his father's triumph at Bouvines. Two years later, invited by English barons in revolt against John, he crossed the Channel and was proclaimed king in London, controlling much of southeastern England. John's death in 1216 rallied support to the young Henry III, and after defeats at Lincoln and in the naval battle off Sandwich in 1217, Louis renounced his claim by the Treaty of Lambeth and withdrew.

Succeeding his father in 1223, he reigned only three years but used them vigorously. He conquered Poitou and Saintonge from the English crown, pushing Plantagenet power south of the Garonne. In 1226 he took command of the Albigensian Crusade, leading a royal army into Languedoc, capturing Avignon after a hard siege, and receiving the submission of much of the south. The campaign decisively committed the monarchy to the absorption of the county of Toulouse, completed under his son.

Returning northward, Louis fell ill with dysentery and died at Montpensier in November 1226, aged thirty-nine. His heir, Louis IX, was a boy of twelve, but the late king's testament entrusted the regency to Blanche of Castile, who defended the child's throne with marked ability. Louis VIII's epithet, "the Lion," reflected the soldierly energy that compressed substantial conquests into one of the shortest reigns of his house.