Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
A new election law had expanded the voting rights to a larger section of the population and established a proportional representation system.
Background
The elections took place in the middle of Biennio Rosso ("Red Biennium") a two-year period, between 1919 and 1920, of intense social conflict in Italy, following the First World War. The revolutionary period was followed by the violent reaction of the Fascistblackshirts militia and eventually by the March on Rome of Benito Mussolini in 1922.
The Biennio Rosso took place in a context of economic crisis at the end of the war, with high unemployment and political instability. It was characterized by mass strikes, worker manifestations as well as self-management experiments through land and factories occupations. In Turin and Milan, workers councils were formed and many factory occupations took place under the leadership of anarcho-syndicalists. The agitations also extended to the agricultural areas of the Padan plain and were accompanied by peasant strikes, rural unrests and guerrilla conflicts between left-wing and right-wing militias.
Electoral system
The Italian parliament passed a law on August 15, 1919 that replaced the uninominal-majoritarian system with a proportional representation system that apportioned seats based on the D'Hondt method.
The new electoral law introduced in 1919 increased the electorate by more than a quarter to 11 million. It gave all those who had fought at the front in the First World War the right to vote, regardless of their age, as well as all other men over the age of 21. The old system of using single-member constituencies with two-round majority voting was abolished and replaced with proportional representation in 58 constituencies with between 5 and 20 members. The new system favoured parties such as the socialist PSI, which was able to mobilise voters through trade unions, cooperatives and other mass organisations, and the Catholic PPI, which could rely on the support of church associations.
^ Brunella Dalla Casa, Composizione di classe, rivendicazioni e professionalità nelle lotte del "biennio rosso" a Bologna, in: AA. VV, Bologna 1920; le origini del fascismo, a cura di Luciano Casali, Cappelli, Bologna 1982, p. 179.