Indeed, the French Navy's technological and numerical edge proved to be decisive in driving the Austrian Navy to port shortly after the outbreak of the Second War of Italian Independence. After the failure of the First Italian War of Independence, Sardinia began the search for potential allies. Sardinian Prime Minister Camillo Benso, Count of Cavour, found French Emperor Napoleon III supportive of an alliance with Sardinia following the Crimean War, in which France and Sardinia were allies against the Russian Empire. After the Plombières Agreement of 1858, Napoleon III and Cavour signed a secret treaty of alliance against Austria whereby France would assist Sardinia in return for Nice and Savoy being ceded to France. During the first half of 1859, the Franco-Sardinian forces quickly defeated the Austrians on land, culminating in the Battle of Solferino, while the French Navy blockaded the Adriatic Sea and forced the Austrian Navy to remain in port, preventing its use for the duration of the war. After the defeat at Solferino, Austria ceded most of Lombardy and the city of Milan to France under the Treaty of Zürich, who transferred it to Sardinia in exchange for Savoy and Nice.