were doing a strike. Ugo Intini wrote: Bombs against the new headquarter in Milan A new attack occurred in Milan during the night between 23 and 24 March 1921: the new headquarter in Via Lodovico da Settala 22 was devastated by bombs thrown by a fascist squad, with the purpose of an immediate retaliation to the massacre of Hotel Diana, provoked a few hours before by some anarchists. In this occasion, Pietro Nenni, still a republican leader at the time, intervened in favour of the socialist newspaper. Director Giacinto Menotti Serrati, after a few days, asked him to go in Paris as correspondent for Avanti!, in trial for six months. Pietro Nenni at Avanti! On 19 April 1921, Nenni signed its first article for the socialist newspaper under the title of "The failure of Versaglia policy". In Paris, Nenni subscribed to PSI and began a path which, in around two years, would lead him to the leadership of the autonomist side of the Party. During the Congress of Milan in 1923, it was in favour of the merger between PSI and the Communist Party of Italy, as imposed by the Soviets and supported by Serrati and the Party secretary Costantino Lazzari. The congress appointed Nenni as new director of Avanti!. Since then, during the whole exile in France and the period of underground in Italy, the relationship between Pietro Nenni and Avanti! had become stronger until 1948. On 31 December 1925, the Mussolini Cabinet made the law n. 2037 on press passed by the Chamber of the Deputies and on 31 October 1926 the newly established fascist regime closed all the publications issued by the opposition. Avanti!, like all the other antifascist newspapers, was obliged to interrupt their prints in Italy but continued to be published in exile, under the impulse of Nenni, in Paris and Zürich every week. Fall of fascism and 1946 referendum Underground Avanti! The socialist newspaper reappeared in Italy in hiding on 11 January 1943: a publication named Avanti!, without using the historical header with an italic type in liberty style, was distributed as the giornale del Movimento di Unità Proletaria per la repubblica socialista ("newspaper of the Movement of Proletarian Unity for the socialist republic"). After the establishment of the Italian Socialist Party of Proletarian Unity (PSIUP) on 22 August 1943 (with the merger between the Italian Socialist Party and the Movement of Proletarian Unity),