Louis VIII (1187–1226), king of France. The only son of Philip II Augustus and Isabella of Hainaut, he was born in Paris on Sept. 5, 1187. When his mother died two years later, Louis inherited the valuable county of Artois, which had been Isabella's dowry, but he had little freedom of action in his lands as long as his father lived. In 1200, Louis married Blanche of Castile, niece of King John of England and granddaughter of King Henry II of England and Eleanor of Aquitaine. Although his health was frail throughout his life, Louis pursued an active military career and sired a large family.
In 1214, when his father faced an invasion from the Netherlands led by Holy Roman Emperor Otto IV, Louis was charged with blocking the advance of Otto's ally, the English King John, in Anjou. He halted John at La-Roche-aux-Moines, near Angers, in June and forced him to retreat. Two years later, Louis himself invaded England at the invitation of barons who were rebelling against John. Louis claimed the royal title through his wife, Blanche, and conquered most of eastern England. Supported by most lay lords but opposed by the higher clergy, he was finally defeated at Lincoln in May 1217 and agreed to leave England in return for an indemnity.
Reign
At the death of Philip Augustus in 1223, Louis VIII became king. In 1224, when the truce with England expired, he conquered English-held Poitou, extending French royal territory to the Bay of Biscay.
Louis VIII's greatest military activity was directed against the Albigensian heretics in southern France. The so-called Albigensian Crusade had been in progress since 1209. Louis had made a brief expedition in 1215 and led a more extensive one in 1219, when he sacked Marmande but failed to take Toulouse. After he became king, he proposed to launch a decisive campaign against Raymond VII, Count of Toulouse. Taking the cross late in January 1226, Louis went south with a large army, successfully besieged Avignon, and then subdued the rest of Languedoc. After taking measures against heresy, he returned northward, but fell ill and died in Montpensier on November 8. His son Louis IX succeeded him (Henneman, John B. "Louis VIII (France) (1187–1226)." Encyclopedia Americana. Grolier Online, 2012. Web. 31 Jan. 2012)