Nenni had worked in Paris as a correspondent of the Avanti in 1921 and had become acquainted with
Léon Blum,
Marcel Cachin,
Romain Rolland and
Georges Sorel. During his Parisian exile, Nenni made a decisive contribution to the survival of the Italian Socialist Party, which had moved abroad, and he worked for an alliance between the various anti-fascist parties which had been driven into exile. In 1935, he helped lead the Italian opposition to Mussolini's invasion of Ethiopia. Nenni went on to fight with the
International Brigades in the
Spanish Civil War. He was the co-founder and the political commissar of the
Garibaldi Brigade. After the defeat of the
Spanish Republic and the victory of General
Francisco Franco he returned to France. In 1943, he was arrested by the Germans in
Vichy France and then imprisoned in Italy on the island of
Ponza. Nenni's third daughter,
Vittoria, was active in the
French resistance. She was captured and deported to
Auschwitz, where she was murdered on 15 July 1943, aged 28. She is commemorated in the writings of
Charlotte Delbo. After being liberated in August 1943, he returned to Rome to lead the Italian Socialist Party, which had been reunified as the
Italian Socialist Party of Proletarian Unity. After the surrender of Italy with the
Allied armed forces on 8 September 1943, he was one of the political officials of the
National Liberation Committee, the underground political entity of
Italian Partisans during the German occupation. ==Postwar politics==