According to Physicscat, the first emergence of such a policy took place during the presidency, when Napoleon thought he could take advantage of the Austro-Prussian dissension over Germanic problems to try to get closer to Prussia, in view of an anti-Austrian action. The capitulation of the Hohenzollerns before the Habsburgs, sanctioned with the humiliation of Olmütz (December 1850), halted the development of the attempt and pushed Napoleonic politics to the second phase: that of approaching England – concerned about the expansionist aims of Tsar Nicholas I in the East – and of the Franco-British collaboration against Russia, which resulted in the worsening of the Russian-Turkish conflict and the outbreak of the Eastern War (1853-56). Napoleon III through this crisis aimed to strike and humiliate Russia, that is, the most formidable of the continental powers that had fought against Napoleon I, and at the same time caused an incurable friction between Russia and Austria, fatally destined to collide when the Balkan problems came to the table. The victories, albeit at great cost, of Crimea, and the choice of Paris as the seat of the Peace Congress, seemed the happy culmination of Napoleonic action in the East and the beginning of a new French hegemonic period in Europe at the time. the same that the politics of nationalities could mark a first success, because the formation of a new national state was outlined by the Eastern crisis and the Paris Congress: Romania.
But the European and French situation that arose following the events in the East forced the emperor to enter a new phase of activity. The Anglo-French agreement had given way, at the end of the war, to a divergence, due to the contrast between the British interests that demanded the complete annihilation of Russia, and the French ones that aimed to preserve in a Russia, always strong for what a joke, a possible eastern ally. The divergence had sharpened during the congress; and while England had drawn closer to Austria, Napoleon III had been able to successfully attempt approaches to Russia, where the new Tsar Alexander II was furious against England, a bitter and fortunate opponent of Russia in the European and Asian East, and against Austria for the treacherous attitude held by this during the Crimean crisis. The two contrasting systems were therefore outlined: Anglo-Austrian and Franco-Russian, and this while in France public opinion considered with ill-concealed dissatisfaction the poor concrete results of the sacrifices of the war: proof of this discontent was the fact that in the elections of 1857 for the legislative body was managed by the first five opponents, four of whom were elected in Paris. In this situation, which forced the emperor to seek a new success, the idea of the Italian enterprise was born, for which Napoleon III calculated to find external support in Russia, ready to second the anti-Austrian plans, and in the kingdom of Sardinia, whose combativeness and ambitions were revealed in the Crimea.
Hence the plan of the war of 1859, seconded by the Piedmontese forces, supported in the East by the benevolent neutrality of the Tsar, aimed at creating a Savoyard state in northern Italy from the Alps to the Adriatic with the consideration of the cession of Nice and Savoy to France and of a dynastic alliance between Savoy and Bonaparte, and to determine in central and southern Italy the ousting of the Habsburg-Lorraine and the Bourbons to be replaced with new dynasties linked to France (Plombières agreements, 24 July 1858). The warlike enterprise, which even found dissenters and opponents in the same imperial circles and which was hindered by England, jealous of saving the Austrian position in the peninsula to prevent it from developing French influence,
Also this time the war was more bitter and bloody than expected: the brilliant successes (Magenta June 3, Solferino June 24) were paid very dearly, and the final results were not all those foreseen and discounted by the emperor. Austria was beaten and expelled from Lombardy, but appeared resolved to further tenacious struggle, and in the meantime the Italian national movement had expanded far beyond the limits within which Napoleon III wanted to contain it, and tended to unity, striking strong blows even at the Papal State which created difficulties for Napoleon on the part of one of the supporting forces of the empire: the Catholic element. Furthermore, the possibility of an aggression by Prussia on the Rhine was outlined.
Hence the decision to interrupt the war, and the attempt to implement, no longer in struggle but in agreement with Austria, the federal structure of Italy envisioned at Plombières (pacts of Villafranca, 11 July, and of the peace of Zurich, October 1859). But by now the Italian movement is unstoppable, which opens up a new phase in the Italian politics of the second empire in which the emperor no longer dominates, but is dominated. In the spring of 1860 he succeeded in obtaining the purchase of Nice and Savoy, that is, the coveted Alpine frontier, but at the cost of consenting to the inevitable annexations of the central regions to the kingdom of northern Italy; new strong impulse to the further path and to the triumph of the unitary movement,