A revolution in fact began on 2 July 1820 in the Kingdom of the Two Sicilies (Naples and Sicily), inspired by the revolution in Spain and led by supporters of the Carbonari, a secret society with roots in revolutionary France. The rebels forced Ferdinand I to accept a written constitution, based on the Spanish Constitution of 1812, but in March 1821 the revolution was put down by an army from Metternich’s Austria. Shelley’s ‘Ode to Naples’, written in August 1820 and published in the Morning Chronicle on 26 September 1820, supported the rebels' cause.

See Morning Chronicle, 26 September 1820; Charles Breunig and Matthew Levinger, The Revolutionary Era, 1789-1840, 3rd edn (New York and London: Norton, 2002), pp. 185-7 and Cian Duffy, ‘“The City Disinterred”: The Shelley Circle and the Revolution at Naples’, Forum for Modern Language Studies, 39.2 (April 2003), 152-164.