"[8] To make up for his distress when the object of his affection married someone else, Sonnino took to long solitary walks and threw himself obsessively into work as he sought career success as a sort of consolation prize for his broken heart.

[8] After graduating in law in Pisa in 1865, Sonnino became a diplomat and an official at the Italian embassies in Madrid, Vienna, Berlin, Paris and Saint Petersburg from 1866 to 1873.

Leopoldo Franchetti's half of the report, Political and Administrative Conditions in Sicily, was an analysis of the Mafia in the 19th century that is still considered authoritative today.

[9] In 1878, Sonnino and Franchetti started a newspaper, La Rassegna Settimanale, which changed from weekly economic reviews to daily political issues.

[16] After the fall of the Crispi government as a result of the lost Battle of Adwa in March 1896, he served as the leader of the opposition conservatives against the liberal Giovanni Giolitti.

In January 1897, Sonnino published an article, Torniamo allo Statuto (Let's go back to the Statute), in which he sounded the alarm about the threats that the clergy, the republicans and the socialists posed to liberalism.

He called for the abolition of the parliamentary government and the return of the royal prerogative to appoint and to dismiss the prime minister without consulting parliament, which he considered to be the only possible way to avert the danger.

[4] In response to the social reforms presented by Prime Minister Giuseppe Zanardelli in November 1902,[18] Sonnino introduced a reform bill to alleviate poverty in southern Italy that provided for a reduction of the land tax in Sicily, Calabria and Sardinia; the facilitation of agricultural credit; the re-establishment of the system of a perpetual lease for smallholdings (emphyteusis) and the dissemination and the enhancement of agrarian contracts to combine the interests of farmers with those of the landowners.

[19] Sonnino criticised the usual approach to solve the crisis through public works: "to construct railways where there is no trade is like giving a spoon to a man who has nothing to eat.

[24] However, after becoming Foreign Minister in November 1914 in the conservative government of Antonio Salandra and realising that it was unlikely to secure Austro-Hungarian agreement to concede territories to Italy, he sided with the Triple Entente of the United Kingdom, France and Russia, and he sanctioned the secret Treaty of London in April 1915 to fulfil Italian irredentist claims.

[24][25] During the talks, Sonnino omitted to include the largely Italian-speaking Austrian city of Fiume (modern Rijeka, Croatia) into the lands that were to go to Italy, an omission that he later would regret in 1919.

[27] In October 1917, the Regio Esercito was badly defeated by an Austro-German force in the Battle of Caporetto, and for a moment it appeared possible that Italy was going to be knocked out of the war.

[28] Sonnino was greatly upset at the Bolsheviks for publishing the Treaty of London, especially as the related diplomatic correspondence to the negotiations made him look petty and selfish as he demanded various parts of the Austrian and Ottoman empires as the reward for entering the war on the Allied side.

In response to the initial success of the Kaiserschlacht with the British and French hard pressed, the Allied armies were finally unified into a Supreme Command under Marshal Ferdinand Foch.

[29] In the fall of 1918 when became clear that Germany was going to lose the war and that the Austrian empire was collapsing, Sonnino pressed very strongly for the Regio Esercito to go on the offensive as he argued that another Italian victory would help Italy achieve what had been promised in the Treaty of London.

[30] However, Sonnino went to Paris, promising in public that national self-determination was to be the basis of the post-world order without being opposed in private, a sleight-of-hand argument that Wilson at first took at face value.

[26] Victor Emmanuel was close to the generals of the Regio Esercito, who advised against annexing Dalamatia under the grounds that garrisoning it would represent an intolerable financial burden on the Italian state.

[27] However, the king did not wish to appear "unpatriotic" by dismissing Sonnino and instead ordered the Italian delegation to secure as much of Italy's "just aspirations" as possible in Paris.

[26] Sonnino often argued to Wilson that because Italy lost half-million killed in the war that felt the Allies had an obligation to fulfil all of the terms of the Treaty of London.

[35] On 24 April 1919, Orlando and Sonnino along with the rest of the Italian delegation walked out of the Paris peace conference in protest over the unwillingness of Wilson to support applying the Treaty of London plus adding Fiume.

[37] Bosworth argued that given the antipathy of Wilson that Sonnino did in fact do fairly well at the Paris peace conference as he won for Italy the Austrian province of South Tyrol (modern Trentino-Alto Adige/Südtirol), the ethnically mixed city of Trieste and parts of Istria where Slovenes were in the majority.

[6] The only Protestant leader in Italian politics, Sonnino was described as "decidedly British in manner and thought" and "the great puritan of the Chamber, the last uncorrupted man".

His stern intransigent moralism made him a difficult man, and although his integrity was universally respected, his closed and taciturn personality gained him few friends in political circles.