Second Italian War of Independence

The immediate occasion for war was Austria's ultimatum to the Kingdom of Sardinia in April 1859, demanding that Sardinia disarm within three days — a demand that Sardinian chief minister Count Camillo di Cavour had, by careful diplomatic preparation, made impossible to accept^[1]. Austria's ultimatum handed Cavour precisely the casus belli he had been engineering, and its rejection brought French imperial forces across the Alps under the terms of a secret alliance negotiated at Plombières in July 1858. What appeared as Austrian aggression was in fact the culmination of a sustained Piedmontese strategy to internationalize the Italian question.

The structural cause was Austrian domination of the Italian peninsula. Austria held Lombardy and Venetia directly as crown provinces and exercised decisive influence over the secondary Italian states through treaty rights, dynastic ties, and garrison rights. For the liberal-nationalist movement that had grown steadily since the 1820s, and particularly since the revolutionary upheavals of 1848–49, Austrian power was the principal obstacle to any form of Italian political consolidation^[2]. The Kingdom of Sardinia — specifically its Piedmontese core — had emerged from 1849 as the only Italian state that retained a constitutional government, giving it the natural leadership role in any future national movement. Cavour's entire foreign policy from 1852 onward was built around the premise that expelling Austria required a great-power ally, and that the ally had to be France.

The Franco-Sardinian alignment was as much Napoleon III's project as Cavour's. The French emperor harbored nationalist sympathies shaped by his own Italian youth and revolutionary associations, and he saw an opportunity to revise the conservative settlement of 1815, extend French prestige, and acquire territorial compensation — specifically Savoy and Nice — in exchange for military intervention^[1]. The Plombières agreement committed France to go to war alongside Sardinia if Austria could be provoked into striking first, a condition essential for Napoleon to maintain domestic and diplomatic credibility.

The ideological dimension cannot be separated from the diplomatic one. The Risorgimento, the broad cultural and political movement for Italian national renewal, had by 1859 generated a substantial base of liberal opinion across the peninsula that framed Austrian rule as both an alien occupation and a barrier to representative government^[2]. Volunteer formations and conspiratorial networks — most visibly associated with figures such as Giuseppe Garibaldi — provided the popular energy that Cavour's cabinet sought to harness and direct. The volunteer corps that would distinguish itself at Varese and San Fermo in the opening weeks of the campaign was an expression of that mobilized nationalist sentiment operating alongside, and sometimes in tension with, the regular Franco-Sardinian military effort.

Austria's own miscalculations accelerated the crisis. Facing financial strain and military overextension, Vienna chose confrontation over negotiation at precisely the moment when Cavour had aligned Sardinia's international position most favorably^[3]. The April ultimatum, by giving Sardinia the appearance of the aggrieved party, consolidated French support and neutralized Prussian hesitation to intervene on Austria's behalf. The battles that followed — at Montebello, Magenta, and finally the bloody engagements at Solferino and San Martino — were the military consequence of a political trap Austria had walked into with its eyes open.

The war ended not with a comprehensive peace congress but with a pair of separate agreements negotiated under the pressure of Napoleon III's unilateral decision to halt the campaign. The Armistice of Villafranca, concluded between Napoleon III and Emperor Franz Joseph in July 1859, suspended hostilities before the Franco-Sardinian forces could advance on the Austrian Quadrilateral fortresses. Its terms were subsequently given diplomatic form in the Treaty of Zurich later that year^[1]. Austria ceded Lombardy to France, which in turn transferred it to Sardinia — a deliberate procedural step intended to honor the letter of Austrian objections to direct cession. Venetia, however, remained under Habsburg rule, a result that deeply embittered Sardinian premier Count Camillo di Cavour, whose strategy had anticipated a more thoroughgoing expulsion of Austria from the peninsula^[2]. Cavour resigned in protest, though he returned to office within a year.

The political consequences within the Italian peninsula moved faster than the diplomats had anticipated. The war's conduct had destabilized the smaller central Italian states — Tuscany, Parma, Modena, and the Papal Legations — whose rulers fled or were deposed during the fighting. Popular assemblies in these territories voted for annexation to Sardinia, and plebiscites held in early 1860 ratified the merger. France extracted its own price for acquiescing in this expansion: the Treaty of Turin (1860) ceded Nice and Savoy to France, the territorial reward that Napoleon III had sought from the outset of his intervention^[1]. Sardinia thus simultaneously gained a large swath of northern and central Italy and surrendered the dynasty's ancestral homeland and its most strategically significant Alpine frontier.

For the broader process of Italian unification, the war of 1859 served as the decisive enabling event. The enlarged Kingdom of Sardinia that emerged from the territorial settlements formed the base from which Giuseppe Garibaldi launched his expedition to Sicily and the mainland in 1860, and upon which the Kingdom of Italy was proclaimed in 1861. Yet the war's incompleteness — specifically the Austrian retention of Venetia — ensured that unification remained a contested project. Venetia was acquired only after Sardinia allied with Prussia in the Austro-Prussian War of 1866, when Austria's defeat on the northern front compelled the cession of the province despite Sardinian-Italian forces suffering reverses on their own front^[3]. Rome itself remained under French garrison protection until 1870.

The military experience of the campaign left its own institutional mark. The carnage at the Battle of Solferino — one of the largest engagements in Europe since Waterloo — moved the Swiss humanitarian Henry Dunant to press for what became the Geneva Convention of 1864 and the founding of the International Committee of the Red Cross^[1]. The tactical lessons of the campaign, especially the effectiveness of rifled infantry weapons against massed formations, were absorbed with varying degrees of attention by European armies preparing for the conflicts that would follow in the 1860s. Austria's operational performance during the war contributed directly to the army reforms undertaken in Vienna during the early 1860s, reforms that nonetheless proved insufficient when tested again at Königgrätz in 1866.

What the war conspicuously did not settle was the fundamental question of Austrian power in central Europe. The Habsburg Empire emerged from 1859 weakened but intact, its finances strained and its prestige damaged yet its institutional structure unreformed. The dual problem of Venetia and the status of German-speaking Austria within the German Confederation survived the peace of Zurich and would drive European diplomacy for nearly a decade. Italian nationalism had secured a territorial base and a degree of international legitimacy, but the tension between the liberal-parliamentary tradition Cavour represented and the more radical currents embodied by figures such as Garibaldi and Giuseppe Mazzini was deferred rather than resolved by the events of 1859.