Nenni, Pietro (pyĕ`trō nĕn`nē), 1891–1980, Italian journalist and political leader. He was imprisoned in 1911 for his participation in the protest movement against the Italo-Turkish war in Libya. He joined the Socialist party in 1921 and subsequently became Paris correspondent and later editor of the Socialist party newspaper Avanti. As an opponent of Fascism, he was forced to emigrate to France in 1926. He fought against the fascists in Spain during the Spanish civil war. In 1943 he was arrested by the Germans in Vichy France and then imprisoned in Italy. Released in Aug., 1943, he began to reorganize the Italian Socialist party, becoming its secretary-general in 1944. He precipitated a split in the party by entering into a political alliance with the Communists in 1947. This alliance was renounced in 1962, in the "opening to the left" of the Christian Democrats. Nenni served in several postwar cabinets, as deputy prime minister or as minister of foreign affairs. In 1971 he ran unsuccessfully for president of Italy.

Nenni, Pietro (Sandro)

(born Feb. 9, 1891, Faenza, Italy—died Jan. 1, 1980, Rome) Italian politician. He joined the Italian Socialist Party (PSI) in 1921 and edited its newspaper, Avanti! (1922–26). After criticizing the Fascist Party and Benito Mussolini, he was arrested and fled to Paris (1926). In the Spanish Civil War, he cofounded the Garibaldi Brigade. He was imprisoned in Germany and Italy in World War II, then became leader of the PSI; he led the left wing in alliance with the Communist Party until 1956. In 1963 he allied the PSI with the Christian Democrats and served as vice premier in three successive cabinets and as foreign minister (1968–69).