Louis IX, known as Saint Louis, was born on 25 April 1214 in Poissy, France. He became King of France in 1226 at the age of 12 after the death of his father, Louis VIII. His mother, Blanche of Castile, served as regent during his minority and continued to advise him until her death in 1252. Louis's early reign was marked by his mother's efforts to stabilize the kingdom, including her role in concluding the Albigensian Crusade in 1229.As king, Louis IX faced challenges from powerful nobles and external threats, notably from England's Henry III, whom he defeated at the Battle of Taillebourg. He expanded French territory by annexing provinces such as parts of Aquitaine, Maine, and Provence. Louis led two major crusades, the Seventh and Eighth Crusades, against Muslim forces in North Africa and the Holy Land. He was captured during the Seventh Crusade and later died from dysentery during the Eighth Crusade in 1270.Louis IX implemented significant legal reforms, establishing a royal justice system that allowed subjects to appeal directly to the king. He abolished trials by ordeal, introduced the presumption of innocence, and created offices for provosts and bailiffs to oversee justice. His reign is noted for its economic and political stability, and he was respected throughout Christendom for his fairness and integrity.Louis IX was deeply religious, building the Sainte-Chapelle in Paris to house Christian relics. He enforced strict Catholic orthodoxy, including laws against blasphemy and actions against the Jewish population, such as the burning of the Talmud. He expanded the Inquisition and took measures against heretical groups like the Cathars. His commitment to Christianity and his charitable acts contributed to his reputation as a model Christian monarch.Louis IX's reign also saw a flourishing of scholarship and the arts, with Paris emerging as a center of learning. He supported scholars like Thomas Aquinas and promoted Gothic architecture. His diplomatic efforts included treaties with Aragon and England, which helped stabilize his kingdom and enhance his reputation as a mediator in European conflicts.After returning from the Holy Land in 1254, Louis IX continued to engage in diplomacy and governance until his death in 1270. He was succeeded by his son, Philip III. Louis IX was canonized by Pope Boniface VIII in 1297, becoming the only French king to be declared a saint. His legacy includes numerous hospitals and charitable institutions, as well as a lasting influence on French law and governance.