Pamphlet of the Italian Socialist Party of Proletarian Unity, Provincial Federation of Mantua, Matteotti Brigade, addressed to the Milanese workers, reminding them of the celebration, after 23 years, of the "Primo Maggio", May First is the celebration of Labour day in Italy. During the Fascist period, starting in 1924, the celebration was brought forward to 21 April. It was brought back to May 1 after the end of the war, in 1945, keeping the status of public holiday. The Matteotti brigades were, during the Resistance, the partisan groups linked to the Italian Socialist Party of Proletarian Unity (PSIUP). They were one of five major partisan political groups who participated in the national liberation struggle.