Navarre / Louis II le Juste (King Louis II the Just), King of France as Louis XIII

Louis XIII was a monarch of the House of Bourbon who ruled as King of France from 1610 to 1643 and King of Navarre (as Louis II) from 1610 to 1620, when the crown of Navarre was merged with the French crown.

Shortly before his ninth birthday, Louis became king of France and Navarre after his father Henry IV was assassinated. His mother, Marie de' Medici, acted as regent during his minority. Mismanagement of the kingdom and ceaseless political intrigues by Marie and her Italian favourites led the young king to take power in 1617 by exiling his mother and executing her followers, including Concino Concini, the most influential Italian at the French court.

Louis XIII, taciturn and suspicious, relied heavily on his chief ministers, first Charles d'Albert, duc de Luynes then Cardinal Richelieu, to govern the kingdom of France. King and cardinal are remembered for establishing the Académie française, and ending the revolt of the French nobility. The reign of Louis "the Just" was also marked by the struggles against Huguenots and Habsburg Spain.

France's greatest victory in the conflicts against the Habsburg Empire during the period 1635–59 came at the Battle of Rocroi (1643), five days after Louis's death caused by apparent complications of intestinal tuberculosis. This battle marked the end of Spain's military ascendancy in Europe and foreshadowed French dominance in Europe under Louis XIV, his son and successor.

Joan III had reigned in Navarre together with her husband Antoine until his death, and then alone until her own death. Their son Henry became King of France in 1589, taking possession of the kingdom in 1593 as the French Wars of Religion came to a close. Thereafter the crown of Navarre passed to the kings of France. In 1620, the Kingdom was merged into France; however, the French kings continued to use the title King of Navarre until 1791, and it was revived again from 1814 to 1830 during the Bourbon Restoration.

The English translation of the royal style of King Louis XIII was:

(1610–1620) By the Grace of God, Most Christian King of France and Navarre, co-Prince of Andorra, Lord of Béarn, and Donezan; Count of Provence, Forcalquier and the lands adjacent; Dauphin of Viennois, Count of Valentinois and of Diois

(1620–1641) By the Grace of God, Most Christian King of France and Navarre; Count of Provence, Forcalquier and the lands adjacent; Dauphin of Viennois, Count of Valentinois and of Diois

(1641–1643) By the Grace of God, Most Christian King of France and Navarre; Count of Barcelona, Roussillon and Cerdagne; Count of Provence, Forcalquier and the lands adjacent; Dauphin of Viennois, Count of Valentinois and of Diois