Charles as Prince of Asturias in 1765.
Charles IV (1748 - 1819) was King of Spain from 1788 to 1799, and was the last member of the Spanish Bourbons.
Charles was born in Naples, Italy on 11 November 1748 while his father Charles III was King of the Two Sicilies. When his father succeeded to the Spanish throne in 1759, Charles became his heir, the Prince of Asturias. Charles was called el Cazador, the Hunter, because he preferred hunting to affairs of state. After succeeding to the Spanish throne upon the death of his father in 1788, he preferred to allow his wife Maria Luisa to deal with the business of ruling Spain and its vast colonial empire. The queen in turn elevated her lover Manuel Godoy to the position of First Minister. The queen and Godoy had little interest in Spain's American colonies, and they ignored the growth of the settlement of Jefferson in northern New Spain.
The death of King Louis XVI of France in 1793 brought his eleven-year-old son Louis XVII to the French throne under a regency led by his mother Marie Antoinette. In April 1794 Marie Antoinette sought an alliance with her nephew, the Holy Roman Emperor Francis II of Austria, aimed at the conquest of Prussia. When the Habsburg War broke out in April 1795, Queen Maria Luisa and Godoy attempted to remain neutral, but pressure from the French led to a treaty of friendship between the two countries on 12 April. The Franco-Spanish alliance was regarded as threatening by Queen Maria I of Portugal, and she was able to persuade Prime Minister Sir Charles Jenkinson of Great Britain to declare war on the French alliance on 23 August 1795.
The war initially went well for for the French and Austrians, but the British entry into the war resulted in a stalemate that lasted for two years. Meanwhile, the British colonists in the Southern Confederation invaded and annexed Spanish Florida in 1796, then went on to invade Spanish Louisiana. At the same time, the Jeffersonians siezed control of the Province of Tejas, extending their rule south to the Rio Grande.
In 1798 the British and Prussians were able to inflict a crushing defeat on the Austrian and French armies, and negotations for a peace treaty began in Aachen in the early months of 1799. Under the terms of the Treaty of Aix-la-Chapelle of 1 March 1799, Charles IV was deposed, and Prince August Ferdinand of Prussia was placed on the Spanish throne, becoming King Ferdinand VII, the founder of a new Hohenzollern dynasty of Spanish monarchs.
Sobel does not mention the former King Charles' fate, but it is likely that he and his family went into exile in France.
Sobel's source for the reign of Charles IV of Spain is Martin Wilmington's Charles IV and Spain's Lost Opportunities in Mexico (New York, 1959).