NAPOLEON III of France in 1858 and prepared for war with Austria, hoping to acquire the Austrian-held states of Lombardy and Venetia. Napoleon demanded the two states of Nice and Savoy from Piedmont in exchange for French help. Angered by Cavour's audacity, Austria declared war on Piedmont in April 1859.
The war went well for Cavour. French and Piedmontese forces crushed the Austrians and liberated Lombardy.
Then Napoleon stabbed Cavour in the back. He brokered a separate truce with Austria in July that left Venetia in Austria's grip. The Piedmontese state, however, extended its control over Northern Italy when nationalists staged popular votes called plebiscites in Modena, Parma, Tuscany, and Romagna (a Papal State). The people of these territories overwhelmingly voted to join Piedmont. It was now up to Giuseppe Garibaldi to liberate the south.