This was followed by the adoption of the 1948 Constitution of the Republic,[3] created by the Constituent Assembly and representatives from the anti-fascist forces that defeated the Nazis and the Fascists during the liberation of Italy and the Italian civil war.

[4] Although other European countries such as Norway, the Netherlands, and France also had partisan movements and collaborationist governments with Nazi Germany during World War II, armed confrontation between compatriots was most intense in Italy, making the Italian case unique.

The date of April 25 was chosen by convention, as it was the day of the year 1945 when the National Liberation Committee of Upper Italy (CLNAI) - whose command was based in Milan and was chaired by Alfredo Pizzoni, Luigi Longo, Emilio Sereni, Sandro Pertini, and Leo Valiani (present among others the designated president Rodolfo Morandi, Giustino Arpesani, and Achille Marazza) - proclaimed a general insurrection in all the territories still occupied by the Nazi-fascists, indicating to all the partisan forces active in Northern Italy that were part of the Volunteer Corps of Freedom to attack the Nazist and Fascist garrisons by imposing the surrender, days before the arrival of the Allied troops; at the same time, the National Liberation Committee for Northern Italy personally issued legislative decrees,[9] assuming power "in the name of the Italian people and as a delegate of the Italian Government", establishing among other things the death sentence for all fascist hierarchs and other collaborationists of the Nazist occupiers,[10] including Benito Mussolini, who would be shot and killed three days later.

[11] The bill states that:[11] In celebration of the total liberation of the Italian territory, 25 April 1946 is declared a national holiday[12]The anniversary was also celebrated in subsequent years, but only on 27 May 1949, article 2 of law n. 260 "Disposizioni in materia di ricorrenze festive" ("Provisions on festive occasions") made the anniversary a permanent, annual national holiday, together with the Italian national holiday of 2 June:[13] The following days are considered public holidays for the purposes of observing the full holiday schedule and the prohibition of performing certain legal acts, in addition to the day of the national holiday, the following days: [...]25 April, the anniversary of the liberation;[14][...]Central Europe Germany Italy Spain (Spanish Civil War) Albania Austria Baltic states Belgium Bulgaria Burma China Czechia Denmark France Germany Greece Italy Japan Jewish Luxembourg Netherlands Norway Poland Romania Slovakia Spain Soviet Union Yugoslavia Germany Italy Netherlands Portugal Spain Sweden Switzerland United Kingdom United States Public events in commemoration of the event, such as marches and parades, have been organized annually in various Italian cities, especially in those decorated with military valor for the war of liberation.

[19] In 1960, when confidence in the Tambroni government was being discussed in the Senate of the Republic with the parliamentary support of the Italian Social Movement, at the time of the Liberation celebrations the senators of the Italian Social Movement left the chamber, greeted upon their return by sarcastic comments (for example socialist Luigi Renato Sansone is quoted saying "Your thirst has disappeared, as usual").