Italo-Prussian Alliance

Background

After the armistice of Villafranca left the Veneto under Austrian control, Italian Prime Minister Cavour considered securing Austrian withdrawal through an agreement with Prussia. In January 1861, he sent Alfonso La Marmora to Berlin, officially for the coronation of Kaiser Wilhelm I but secretly to explore a possible anti-Austrian pact; the mission failed due to Prussia's wariness of Italy's liberal politics. Between 1861 and 1866, Italy made further attempts to obtain the Veneto from Austria, negotiating through French or British mediation since Austria did not recognize the Kingdom of Italy.

Giuseppe Pasolini tried in December 1863, La Marmora in November 1864, and Count Alessandro Malaguzzi Valeri in October 1865 offered a large sum of money—all without success. In 1865, Prussian Chancellor Otto von Bismarck decided to end Austrian influence over Germany by war and began exploratory contacts with France and Italy. In late July 1865, diplomat Karl von Usedom asked La Marmora what Italy would do in an Austro-Prussian conflict; La Marmora replied cautiously, saying he needed to know Napoleon III's intentions.

On 13 August 1865, French Foreign Minister Drouyn de Lhuys told Italian ambassador Costantino Nigra that France would remain neutral in such a war and would not oppose Italy joining Prussia.

The treaty

By late March 1866, La Marmora had seen a draft treaty from Bismarck and told his Berlin envoy, Giulio De Barral, that Florence liked it. The formal alliance was signed in Berlin on 8 April 1866. De Barral and Govone signed for Italy, Bismarck for Prussia. The treaty promised friendship between the two kings.

If Prussia’s talks to reform the German Confederation failed and it resorted to war, Italy would declare war on Austria as soon as it learned of Prussia’s move. Both sides would fight with all their forces and could not make peace or an armistice without each other’s consent. That consent could not be withheld once Austria gave Lombardy-Venetia to Italy and equivalent Austrian territory to Prussia. The treaty would lapse three months after signing if Prussia had not declared war on Austria.

If the Austrian fleet left the Adriatic before war began, Italy would send enough ships to the Baltic to join the Prussian navy when fighting started. Both sides kept the treaty secret. Bismarck then proposed a new German Confederation without Austria to the Frankfurt Diet. The Diet met the idea with distrust and sarcasm.

French mediation and the end of the alliance

The day before the defeat at Sadowa, the Austrians made a second attempt to break the alliance. During the night of 2–3 July 1866, Emperor Franz Joseph I, warned of impending catastrophe by General Benedek, thought of unconditionally offering the Veneto to Napoleon III to obtain an armistice with Italy. After Sadowa on 4 July, he acted on this, and the offer was communicated to the Austrian ambassador in Paris that evening. Napoleon III, fearing a decisive Prussian success, telegraphed Victor Emmanuel II on 5 July offering the Veneto in exchange for peace with Austria, and published the offer in Le Moniteur Universel to increase pressure.

The Italian government reacted coldly; Prime Minister Ricasoli could not outright refuse French mediation but played for time, continuing military operations. Napoleon also offered mediation to Prussia, which Bismarck accepted, leading to an agreement between Austria and Prussia for a North German Confederation under Prussian leadership and Austria's exclusion from German affairs. A truce was reached. Italy had occupied the Veneto and was converging on Trento.

The truce between Austria and Prussia was decided on 21 July, valid from midday on 22 July. Florence learned of it indirectly through France. Italy sought a military victory and initially told Napoleon it awaited direct communication from Prussia, but after news of the Italian naval defeat at Lissa on 22 July, Italy agreed to a truce on 23 July.

Did You Know?

• Napoleon III advised Italy to accept the alliance with Prussia and promised that France would intervene if Austria attacked Italy first.
• On 5 July 1866, Napoleon III telegraphed Victor Emmanuel II offering the Veneto in exchange for peace with Austria, and published the offer in Le Moniteur Universel to pressure Italy.