Ferdinand I., king of the Two Sicilies, third son of Charles III. of Spain, succeeded his father on the Neapolitan throne (1759), married Maria Caroline, daughter of Maria-Theresa; joined the Allies in the struggle against Napoleon, and in 1806 was driven from his throne by the French, but was reinstated at the Congress of Vienna; in 1816 he constituted his two States (Sicily and Naples) into the kingdom of the Two Sicilies, and in the last four years of his reign ruled, with the aid of Austria, as a despot, and having broken a pledge to his people, was compelled ere his return to grant a popular constitution (1751‒1825).
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Ferdinand III. * Ferdinand II.