Sonnino, a man of the right, had served as a chief critic of the modernizing policies of the latter 19th and early 20th centuries; yet, he favored universal manhood suffrage, labor legislation, and other progressive measures. In 1897, he urged that Italy return, constitutionally, to the Statuto granted to the Piedmontese by King Carlo Alberto in 1848.
Sonnino, twice premier himself, had served as mentor to Antonio Salandra, who became premier in March 1914, and he joined Salandra's cabinet when a death and two resignations forced a reorganization in October-November 1914. Sonnino was accorded equal voice in the choosing of a new cabinet and took the Foreign Ministry portfolio.
In August, Sonnino had favored Italy's entering the war as an ally of Germany and Austria-Hungary; but, soon he came to support the view that pro-Entente intervention would be necessary, if Italy could not gain substantial concessions from Austria-Hungary under terms of their pre-war alliance. Vienna played its part by refusing to negotiate seriously, and Turkey's intervention in favor of the Central Powers on November 3, 1914, increased pressure upon Sonnino to act (See Der Italienische Vertragsentwurf - Documents).
Sonnino then directed the Marchese Guglielmo Imperiali, Italian ambassador in London, in negotiating the Pact of London of April 1915 with Foreign Minister Sir Edward Grey, spokesman for the Entente. The agreement secured Italy's intervention on the side of the Entente, in return for promises of territory in Istria, the Trentino, Dalmatia, and elsewhere, and of British financial assistance (See Documents, April 26, 1915).
As the financial terms demonstrate, everyone involved expected the war to end rather soon after Italian intervention. However, the collapse of the Russian war effort in 1915 ensured that Italian intervention, instead, saved the Entente from defeat.
Sonnino remained foreign minister through the successive governments of Paolo Boselli and V. E. Orlando and resisted Allied efforts to entice Austria-Hungary into a separate peace at the expense of Italy's war aims. At the Paris Peace Conference, he demonstrated tenacity in demanding the fulfillment of the terms of the Pact of London. However, the influence of U.S. President Woodrow Wilson and British Prime Minister David Lloyd George, coupled with Orlando's desire to add Fiume to Italy's claims, served to frustrate Sonnino's ambitions.
Although a man of the right, Sonnino differed from the neo-romantic new right of Salandra's National Policy, Enrico Corridoni's L'Idea Nazionale, and Mussolini's fascism. He rejected Mussolini's overture that he join the fascist regime.
Sidney Sonnino, Opera Omnia di Sidney Sonnino, ed. Benjamin Brown and Pietro Pastorelli (7 vols; Rome-Bari; 1972-75).
&ndsp;&ndsp;&ndsp;&ndsp;&ndsp;Discorsi Parlementari (3 vols, Rome, 1925)