[4] The PSI, which always remained the country's third-largest party, came to special prominence in the 1980s when its leader Bettino Craxi served as Prime Minister of Italy from 1983 to 1987.

During the third congress on 13 January 1895 in Parma, it decided to adopt the name of Italian Socialist Party and Filippo Turati was elected its secretary.

This conciliation with the existing governments and its improving electoral fortunes helped to establish the PSI as a mainstream Italian political party by the 1910s.

In 1914, the party obtained good success in local elections, especially in the industrialised northern Italy, and Mussolini became leader of the City Council of Milan.

The orthodox socialists were challenged by advocates of national syndicalism, who called for revolutionary war to liberate Italian-speaking territories from authoritarian Austrian Empire control and force the government by threat of violence to create a corporatist state.

The national syndicalists intended to support Italian republicans in overthrowing the monarchy if such reforms were not made and if Italy did not enter the war together with the Allied Powers and their struggle against the Central Empires, seen as the final fight for the worldwide triumph of freedom and democracy.

In the 1919 Italian general election, the PSI, led by Nicola Bombacci, reached its highest result ever: 32.0% and 156 seats in the country's Chamber of Deputies.

From 1919 to the 1920s, Socialists and Fascists emerged as prominent rival movements in Italy's urban centres, often resorting to political violence in their clashes.

In the 1948 Italian general election, the United States secretly convinced Britain's Labour Party to pressure Socialists to end all coalitions with Communists, which fostered a split in PSI.

Nonetheless, the PSI continued its alliance with the PCI until 1956, when the Soviet repression of the Hungarian Revolution of 1956 caused a major split between the two parties.

After a disappointing loss in the 1968 Italian general election in which the PSU gained far fewer seats in total than each of the two parties had obtained separately in 1963, it disbanded.

The 1972 Italian general election underlined the PSI's precipitate decline as the party received less than 10% of the vote compared to 14.2% in 1958, when Nenni assumed the leadership of the autonomist faction.

At the same time, the PSI increased its presence in the big state-owned enterprises and became heavily involved in corruption and illegal party funding, which would eventually result in the mani pulite investigations.

Even if the PSI never became a serious electoral challenger either to the PCI or the DC, its pivotal position in the political arena allowed it to claim the post of Prime Minister for Craxi after the 1983 Italian general election.

In fact, the PSI was in line to become the Italy's second largest party and to become the dominant force of a new left-wing coalition opposed to a Christian Democrat-led one; this did not actually happen because of the rise of Lega Nord and the Tangentopoli scandals.

Feeling betrayed, Chiesa confessed his crimes to the police and implicated others, starting a chain reaction of judicial investigations that would ultimately engulf the entire political system.

The investigations, named mani pulite ("clean hands") was carried out by three Milanese magistrates among whom Antonio Di Pietro quickly stood out becoming a national hero thanks to his charismatic character and his ability to extract confessions.

The investigations were suspended for four weeks for the 1992 Italian general election to take place in an uninfluenced atmosphere and the PSI managed to garner 13.6% of the vote in spite of the corruption scandals.

In 1992–1993, many PSI regional, provincial, and municipal deputies, MPs, mayors and even ministers found themselves overwhelmed with accusations and arrests.

Although he had many supporters, Martelli and Craxi were both caught in a scandal dating back to 1982, when the Banco Ambrosiano gave to the two of them around 7 million dollars.

Its remains contested the election as part of the Alliance of Progressives dominated by the post-Communist incarnation of the PCI, the Democratic Party of the Left (PDS).

Del Turco had quickly changed the party symbol to reinforce the idea of innovation, which did not stop the PSI gaining only 2.2% of the votes compared to 13.6% in 1992.

Most Socialists joined other political forces, mainly Forza Italia, the new party led by Silvio Berlusconi, the Patto Segni, and Democratic Alliance.

[citation needed] The party was disbanded on 13 November 1994 after two years in which almost all of its longtime leaders, especially Craxi, were involved in Tangentopoli and decided to leave politics.

Socialists who did not align with the other parties organised themselves in two groups: the Italian Socialists (SI) of Enrico Boselli, Ottaviano Del Turco, Roberto Villetti, Riccardo Nencini, Cesare Marini, and Maria Rosaria Manieri, who decided to be autonomous from the PDS; and the Labour Federation (FL) of Valdo Spini, Antonio Ruberti, Giorgio Ruffolo, Giuseppe Pericu, Carlo Carli, and Rosario Olivo, who entered in close alliance with it.

Between 1994 and 1996, many former Socialists joined Forza Italia (FI), as did Giulio Tremonti, Franco Frattini, Massimo Baldini, and Luigi Cesaro.

Although it may seem unusual for self-identified socialists to be members of a centre-right party, many of those who did so felt that the centre-left was by now dominated by former Communists and the best way to fight for mainstream social democracy was through FI/PdL.

In the 1919 Italian general election, thanks to the electoral reforms of the previous decade and especially the introduction of proportional representation in place of the old first-past-the-post system, they had their best result ever: 32.0% and 156 seats.

[25] During the Italian Resistance, which was fought mostly in Piedmont, Emilia-Romagna, and Central Italy, Communists were able to take roots and organise people much better than Socialists so that at the end of World War II the balance between the two parties was completely changed.

Alongside the high shares of vote in north-western Lombardy and the North-East (both around 18–20%), the PSI did fairly well in Campania (14.9%), Apulia (15.3%), Calabria (16.9%), and Sicily (14.9%).