byname LOUIS THE JUST, French LOUIS LE JUSTE king of France from 1610 to 1643, who cooperated closely with his chief minister, the Cardinal de Richelieu, to make France a leading European power.

In May 1635, France declared war on Spain; and by August 1636 Spanish forces were advancing on Paris. Richelieu recommended evacuation of the city; but Louis, in a surprising display of boldness, overruled him. The King rallied his troops and drove back the invaders. Late in 1638 he suffered a crisis of conscience over his alliances with the Protestant powers, but Richelieu managed to overcome his doubts. Meanwhile, Anne of Austria, who had long been treated with disdain by her husband, had given birth (September 1638) to their first child, the dauphin Louis (the future Louis XIV).

In 1642, Louis's young favourite, the Marquis de Cinq-Mars, instigated the last major conspiracy of the reign by plotting with the Spanish court to overthrow Richelieu; revelation of Cinq-Mars's treason made Louis more dependent than ever on the Cardinal. By the time Richelieu died in December 1642, substantial victories had been won in the war against the Spaniards, and Louis was respected as one of the most powerful monarchs in Europe. The King succumbed to tuberculosis five months later. He was succeeded by his son Louis XIV.