The Aventine Secession was the withdrawal of the parliament opposition, mainly comprising the Italian Socialist Party, Italian Liberal Party, Italian People's Party and Italian Communist Party, from the Chamber of Deputies in 1924–25, following the murder of the deputy Giacomo Matteotti by fascists on 10 June 1924.
The secession was named after the Aventine Secession in ancient Rome. This act of protest heralded the assumption of total power by Benito Mussolini and his National Fascist Party and the establishment of a one-party dictatorship in Italy. It was unsuccessful in opposing the National Fascist Party, and after two years the Chamber of Deputies ruled that the 123 Aventine deputies had forfeited their positions. In the following years, many of the "Aventinian" deputies were forced into exile or imprisoned.
Background
In 1923, the Acerbo Law replaced proportional representation. It meant that the largest party, providing it had at least 25% of the vote, gained 2/3 of the parliamentary seats. Following the elections in April 1924, Mussolini obtained 64.9% of the vote, giving him a clear majority under either system.
After his outspoken accusation of the Fascist Party's underhand methods of political corruption and voter intimidation, the Socialist leader Giacomo Matteotti was abducted and murdered by Amerigo Dumini and various other thugs whose names were linked to the Fascist Party. There is considerable dispute among historians as to the level (if any) of Mussolini's knowledge and involvement.
The resulting uproar after the Matteotti murder left Mussolini vulnerable, having been forced to dismiss numerous members of his entourage, including General De Bono, Chief of Police and Head of the MVSN. In late July 1924, the Socialists, Christian democrats and some Liberals began a boycott of Parliament, with the aim of forcing the King to dismiss Mussolini.
The secession
On 26 June 1924 around 130 of the Italian opposition deputies (including members of the Italian People's Party, Unitary Socialist Party, Italian Socialist Party, Communist Party of Italy, Social Democratic Party, Italian Republican Party, Democratic Liberal Party, and Sardinian Action Party) met in the Sala della Lupa () of the Palazzo Montecitorio. There, they decided to abandon their parliamentary work since the government had not clarified its position on the disappearance of Giacomo Matteotti.
Giovanni Amendola of the Democratic Liberal Party published the reasoning behind the secession in Il Mondo:
The non-violent opposition to the government was also promoted by socialist deputy Filippo Turati. On 27 June 1924, he commemorated Matteotti at the Palazzo Montecitorio in front of the other secessionists.
Other than Mussolini's National Fascist Party, the parties that did not participate in the secession included the Italian Liberal Party, the Peasants' Party of Italy, and the Lists of Slavs and Germans.
The "Aventinians" were mostly against a popular insurrection to depose Mussolini's government. At the same time, the protesting deputies did not coordinate with the other opponents of fascism that did not join the secession and remained in the Italian parliament. The secessionists believed that, before the fascists' link to Matteotti's kidnapping and presumed death became clear, the Italian king would dismiss Mussolini and dissolve the Chamber to call for new elections. None of that happened.
Officer Dumini was arrested on 12 July 1924, at the Roma Termini railway station, as he was preparing to leave for the north of Italy and was brought to the Regina Coeli prison. On 16 August the body of the Matteotti was found in the forest of Quartarella, which agitated the already tense political crisis.
Between August and October 1924, some Aventinian leaders, including Giovanni Amendola, seemed to share the militant insurrectional line proposed by antifascist group Italia Libera. Italia libera secretly brought to Rome an armed group of several thousand men dubbed the "Amici del Popolo" (). In an executive report by the Communist International, Palmiro Togliatti estimated there were 7,000 men in this Roman group, and he believed that around 4,000 could be controlled by Communist infiltrators.
On 12 September 1924 the militant communist killed the fascist deputy to avenge Matteotti, which increased the rigidity of the government position. On 20 October the communist leader Antonio Gramsci proposed that the Aventinian opposition should form an "anti-parliament" to signal the great distance between the secessionists and a Parliament composed only of fascists. The proposal was not executed, however.