Italian Socialist leader who took his party into the Comintern but refused to expel the reformists, causing the Livorno split of 1921
Born in Spotorno, he became a central leader of the Italian Socialist Party and in 1914 succeeded the ousted Mussolini as editor of Avanti!. He pushed the party left during the war, joined the Zimmerwald movement and after the October Revolution led the PSI into the Comintern. At the Second Congress of 1920 he sat on the presiding committee and was elected to the Executive, but in 1921 he rejected the principle of breaking with the reformists and stayed at the head of the Socialist Party as the Communists split away. In 1924 he led the party’s left wing into the Communist Party, and in 1926 died of heart failure on his way to an underground party meeting.