Upon the fall of the French Empire, Ferdinand I was restored to the throne of the Kingdom of the Two Sicilies in 1815, founding the House of Bourbon-Two Sicilies. His subjects revolted in 1820 and he was forced to grant a constitution; Austria invaded in March 1821 and revoked the constitution. He was succeeded by his son, Francis I, in 1825 and by his grandson, Ferdinand II, in 1830. Another revolution erupted in January 1848 and Ferdinand was also forced to grant a constitution. This constitution was revoked in 1849. Ferdinand was succeeded by his son, Francis II, in May 1859.