The War of 1859: Magenta, Solferino and Villafranca

In April 1859 Austria issued an ultimatum demanding that Piedmont disarm, and when Piedmont refused, Austria declared war, exactly as Cavour had hoped. French and Piedmontese armies defeated the Austrians at Magenta on 4 June and at Solferino on 24 June, two of the bloodiest battles of the century.

Then Napoleon III, alarmed by the casualties, by Prussian mobilization on the Rhine and by the spread of revolution in central Italy, made a sudden armistice with Austria at Villafranca on 11 July without consulting Cavour; Piedmont gained Lombardy, but Austria kept Venetia. Cavour resigned in fury, though he returned to office in January 1860.

Meanwhile popular movements in Tuscany, Parma, Modena and the papal Romagna expelled their rulers and voted, in plebiscites held in March 1860, to join Piedmont. To win French approval, Piedmont ceded Nice and Savoy to France. The war showed how unification moved forward through a mix of foreign armies, local uprisings and diplomatic bargaining.