Kings Louis IX of France and Henry III of England agree to the Treaty of Paris, in which Henry renounces his claims to French-controlled territory on continental Europe (including Normandy) in exchange for Louis withdrawing his support for English rebels.

Henry III (1 October 1207 16 November 1272), also known as Henry of Winchester, was King of England, Lord of Ireland, and Duke of Aquitaine from 1216 until his death in 1272. The son of King John and Isabella of Angoulme, Henry assumed the throne when he was only nine in the middle of the First Barons' War. Cardinal Guala declared the war against the rebel barons to be a religious crusade and Henry's forces, led by William Marshal, defeated the rebels at the battles of Lincoln and Sandwich in 1217. Henry promised to abide by the Great Charter of 1225, a later version of the 1215 Magna Carta, which limited royal power and protected the rights of the major barons. His early rule was dominated first by Hubert de Burgh and then Peter des Roches, who re-established royal authority after the war. In 1230, the King attempted to reconquer the provinces of France that had once belonged to his father, but the invasion was a debacle. A revolt led by William Marshal's son, Richard Marshal, broke out in 1232, ending in a peace settlement negotiated by the Church.

Following the revolt, Henry ruled England personally, rather than governing through senior ministers. He travelled less than previous monarchs, investing heavily in a handful of his favourite palaces and castles. He married Eleanor of Provence, with whom he had five children. Henry was known for his piety, holding lavish religious ceremonies and giving generously to charities; the King was particularly devoted to the figure of Edward the Confessor, whom he adopted as his patron saint. He extracted huge sums of money from the Jews in England, ultimately crippling their ability to do business, and as attitudes towards the Jews hardened, he introduced the Statute of Jewry, attempting to segregate the community. In a fresh attempt to reclaim his family's lands in France, he invaded Poitou in 1242, leading to the disastrous Battle of Taillebourg. After this, Henry relied on diplomacy, cultivating an alliance with Frederick II, Holy Roman Emperor. Henry supported his brother Richard of Cornwall in his bid to become King of the Romans in 1256, but was unable to place his own son Edmund Crouchback on the throne of Sicily, despite investing large amounts of money. He planned to go on crusade to the Levant, but was prevented from doing so by rebellions in Gascony.

By 1258, Henry's rule was increasingly unpopular, the result of the failure of his expensive foreign policies and the notoriety of his Poitevin half-brothers, the Lusignans, as well as the role of his local officials in collecting taxes and debts. A coalition of his barons, initially probably backed by Eleanor, seized power in a coup d'tat and expelled the Poitevins from England, reforming the royal government through a process called the Provisions of Oxford. Henry and the baronial government enacted a peace with France in 1259, under which Henry gave up his rights to his other lands in France in return for King Louis IX recognising him as the rightful ruler of Gascony. The baronial regime collapsed but Henry was unable to reform a stable government and instability across England continued.

In 1263, one of the more radical barons, Simon de Montfort, seized power, resulting in the Second Barons' War. Henry persuaded Louis to support his cause and mobilised an army. The Battle of Lewes occurred in 1264, where Henry was defeated and taken prisoner. Henry's eldest son, Edward, escaped from captivity to defeat de Montfort at the Battle of Evesham the following year and freed his father. Henry initially enacted a harsh revenge on the remaining rebels, but was persuaded by the Church to mollify his policies through the Dictum of Kenilworth. Reconstruction was slow and Henry had to acquiesce to various measures, including further suppression of the Jews, to maintain baronial and popular support. Henry died in 1272, leaving Edward as his successor. He was buried in Westminster Abbey, which he had rebuilt in the second half of his reign, and was moved to his current tomb in 1290. Some miracles were declared after his death; however, he was not canonised. Henry's reign of fifty-six years was the longest in medieval English history and would not be surpassed by an English, or later British, monarch until that of George III in the nineteenth century.

Louis IX (25 April 1214 – 25 August 1270), commonly known as Saint Louis or Louis the Saint, was King of France from 1226 to 1270, and the most illustrious of the Direct Capetians. He was crowned in Reims at the age of 12, following the death of his father Louis VIII. His mother, Blanche of Castile, ruled the kingdom as regent until he reached maturity, and then remained his valued adviser until her death. During Louis' childhood, Blanche dealt with the opposition of rebellious vassals and secured Capetian success in the Albigensian Crusade, which had started 20 years earlier.

As an adult, Louis IX faced recurring conflicts with some of his realm's most powerful nobles, such as Hugh X of Lusignan and Peter of Dreux. Simultaneously, Henry III of England attempted to restore the Angevin continental possessions, but was promptly routed at the Battle of Taillebourg. Louis annexed several provinces, notably parts of Aquitaine, Maine and Provence.

Louis IX enjoyed immense prestige throughout Christendom and was one of the most notable European monarchs of the Middle Ages. His reign is remembered as a medieval golden age in which the Kingdom of France reached an economic as well as political peak. His fellow European rulers esteemed him highly for his skill at arms, the power and unmatched wealth of his kingdom, but also for his reputation for fairness and moral integrity; he was often asked to arbitrate their disputes.He was a reformer and developed a process of French royal justice in which the king was the supreme judge to whom anyone could in theory appeal for the amendment of a judgment. He banned trials by ordeal, tried to end the scourge of private wars, and introduced the presumption of innocence to criminal procedures. To enforce his new legal system, Louis IX created provosts and bailiffs.

Honoring a vow he had made while praying for recovery during a serious illness, Louis IX led the ill-fated Seventh Crusade and Eighth Crusade against the Muslim dynasties that ruled North Africa, Egypt and the Holy Land in the 13th century. He was captured in the first and ransomed, and he died from dysentery during the latter. He was succeeded by his son Philip III.

His admirers through the centuries have regarded Louis IX as the ideal Christian ruler. He was a splendid knight whose kindness and engaging manner made him popular, though contemporaries occasionally rebuked him as a "monk king". He was seen as inspired by Christian zeal and Catholic devotion. Enforcing strict Catholic orthodoxy, his laws punished blasphemy by mutilation of the tongue and lips, and he ordered the burning of some 12,000 manuscript copies of the Talmud and other important Jewish books after the Disputation of Paris of 1240. He is the only canonized king of France, and there are consequently many places named after him.