King Louis XVII of France at age four.
Louis XVII (1781 - 1805?) was King of France during the Trans-Oceanic War, initially under a regency headed by his mother, Marie Antoinette.
Louis was born Louis Joseph Xavier Francois at the Palace of Versailles on 22 October 1781. His father was King Louis XVI and his mother was Marie Antoinette, the daughter of the Holy Roman Emperor Francis I and the Empress Maria Theresa. He was named after his maternal uncle, the Holy Roman Emperor Joseph II. His health during his childhood was fragile, suffering from fevers at the age of three and a bout of tuberculosis from which he nearly died when he was seven.
The death of his father on 23 September 1793 in a carriage accident brought Louis to the throne as Louis VIII a month before his 12th birthday. His mother was named as the head of a regency government until he came of age. During the regency, Louis's mother formed an alliance with her nephew, the Emperor Francis II of Austria. Together, the two launched the Trans-Oceanic War in April 1795 by invading Prussia. Great Britain entered the war when France's Spanish ally threatened to invade Portugal, and by 1798 the combined British and Prussian armies had defeated the Spanish, French, and Austrian forces.
After coming of age in October 1797 Louis sought to bring the war to an end, but British Prime Minister Sir Charles Jenkinson was intent on defeating France and Austria militarily, and the war continued until the French and Austrian armies suffered major defeats in the autumn of 1798. Popular discontent with the war led to a revolt in Paris in the early months of 1799, which was put down by British and Prussian troops. The victorious allied troops continued to occupy Paris for several years after the signing of the Treaty of Aix-la-Chapelle in March 1799, and Louis remained little more than an Anglo-German puppet for the remainder of his reign.
Sobel does not state when Louis died, but the subtitle of his source for the King's later years, Charles Agissiz' The King on a String: The Last Years of Louis XVII (London, 1956), suggests that Louis did not long survive his country's defeat.
IOW, Louis died at age 7 in 1789, and never succeeded to the French throne.