Editing Ferdinand I of the Two Sicilies (section)

==1820 revolution==
[[File:Palermo insurrection of 1820.jpg|thumb|left|Palermo insurrection of 1820]]

The suppression of liberal opinion caused an alarming spread of the influence and activity of the secret society of the [[Carbonari]], which in time affected a large part of the army.<ref name=EB1911/> In July 1820, a military revolt broke out under General [[Guglielmo Pepe]], and Ferdinand was terrorised into signing a constitution on the model of the [[Spanish Constitution of 1812]]. On the other hand, a revolt in [[Sicily]], in favour of the recovery of its independence, was suppressed by Neapolitan troops.

The success of the military revolution at Naples seriously alarmed the powers of the [[Holy Alliance]], who feared that it might spread to other Italian states and so lead to a general European conflagration. The [[Troppau Protocol]] of 1820 was signed by Austria, [[Prussia]] and Russia, although an invitation to Ferdinand to attend the adjourned [[Congress of Laibach]] (1821) was issued at which he failed to distinguish himself. He had twice sworn to maintain the new constitution but was hardly out of Naples before he repudiated his oaths and, in letters addressed to all the sovereigns of Europe, declared his acts to have been null and void. Metternich had no difficulty in persuading the king to allow an Austrian army to march into Naples "to restore order".<ref name=EB1911/>

The Neapolitans, commanded by General Pepe, made no attempt to defend the difficult [[defile (geography)|defile]]s of the [[Abruzzi]],<ref name=EB1911>{{EB1911|wstitle=Ferdinand IV. of Naples|volume=10|pages=264–265|inline=1}}</ref> and were defeated at [[Battle of Rieti]] (7 March 1821). The Austrians entered Naples.