Marriage in Paris, France, of the Huguenot King Henry III of Navarre to Margaret of Valois, in a supposed attempt to reconcile Protestants and Catholics.

Henry IV (French: Henri IV; 13 December 1553 14 May 1610), also known by the epithet Good King Henry or Henry the Great, was King of Navarre (as Henry III) from 1572 and King of France from 1589 to 1610. He was the first monarch of France from the House of Bourbon, a cadet branch of the Capetian dynasty. He was assassinated in 1610 by Franois Ravaillac, a Catholic zealot, and was succeeded by his son Louis XIII.

The son of Antoine de Bourbon, Duke of Vendme and Jeanne d'Albret, the Queen of Navarre, Henry was baptised as a Catholic but raised in the Protestant faith by his mother. He inherited the throne of Navarre in 1572 on his mother's death. As a Huguenot, Henry was involved in the French Wars of Religion, barely escaping assassination in the St. Bartholomew's Day massacre. He later led Protestant forces against the royal army.

Henry and his predecessor Henry III of France were direct descendants of King Louis IX. Henry III belonged to the House of Valois, descended from Philip III of France, elder son of Saint Louis; Henry IV belonged to the House of Bourbon, descended from Robert, Count of Clermont, younger son of Saint Louis. As Head of the House of Bourbon, Henry was "first prince of the blood". Upon the death of his brother-in-law and distant cousin Henry III in 1589, Henry was called to the French succession by the Salic law.

He initially kept the Protestant faith (the only French king to do so) and had to fight against the Catholic League, which denied that he could wear France's crown as a Protestant. After four years of stalemate, he converted to Catholicism to obtain mastery over his kingdom (reportedly saying, "Paris is well worth a mass"). As a pragmatic politician (in the parlance of the time, a politique), he promulgated the Edict of Nantes (1598), which guaranteed religious liberties to Protestants, thereby effectively ending the French Wars of Religion.

An active ruler, Henry worked to regularise state finance, promote agriculture, eliminate corruption and encourage education. During his reign, the French colonization of the Americas truly began with the foundation of the colonies of Acadia and Canada at Port-Royal and Quebec, respectively. He is celebrated in the popular song "Vive le roi Henri" (which later became an anthem for the French monarchy during the reigns of his successors) and in Voltaire's Henriade.

The Huguenots ( HEW-gə-nots, also UK: -⁠nohz, French: [yɡ(ə)no]) were a religious group of French Protestants who held to the Reformed, or Calvinist, tradition of Protestantism. The term, which may be derived from the name of a Swiss political leader, the Genevan burgomaster Bezanson Hugues (1491–1532?), was in common use by the mid-16th century. Huguenot was frequently used in reference to those of the Reformed Church of France from the time of the Protestant Reformation. By contrast, the Protestant populations of eastern France, in Alsace, Moselle, and Montbéliard, were mainly Lutherans.

In his Encyclopedia of Protestantism, Hans Hillerbrand wrote that on the eve of the St. Bartholomew's Day massacre in 1572, the Huguenot community made up as much as 10% of the French population. By 1600 it had declined to 7–8%, and was reduced further late in the century after the return of persecution under Louis XIV, who instituted the dragonnades to forcibly convert the Protestants, and then finally revoked all Protestant rights in his the Edict of Fontainebleau of 1685.

The Huguenots were concentrated in the southern and western parts of the Kingdom of France. As Huguenots gained influence and more openly displayed their faith, Catholic hostility grew. A series of religious conflicts followed, known as the French Wars of Religion, fought intermittently from 1562 to 1598. The Huguenots were led by Jeanne d'Albret; her son, the future Henry IV (who would later convert to Catholicism in order to become king); and the princes of Condé. The wars ended with the Edict of Nantes, which granted the Huguenots substantial religious, political and military autonomy.

Huguenot rebellions in the 1620s resulted in the abolition of their political and military privileges. They retained the religious provisions of the Edict of Nantes until the rule of Louis XIV, who gradually increased persecution of Protestantism until he issued the Edict of Fontainebleau (1685). This ended legal recognition of Protestantism in France and the Huguenots were forced to either convert to Catholicism (possibly as Nicodemites) or flee as refugees; they were subject to violent dragonnades. Louis XIV claimed that the French Huguenot population was reduced from about 900,000 or 800,000 adherents to just 1,000 or 1,500. He exaggerated the decline, but the dragonnades were devastating for the French Protestant community.

The remaining Huguenots faced continued persecution under Louis XV. By the time of his death in 1774, Calvinism had been nearly eliminated from France. Persecution of Protestants officially ended with the Edict of Versailles, signed by Louis XVI in 1787. Two years later, with the Revolutionary Declaration of the Rights of Man and of the Citizen of 1789, Protestants gained equal rights as citizens.