On March 18, 1848 Milan efficaciously rebelled against Austrian rule, during the so-called "Five Days" (), that forced Field Marshal Radetzky to temporarily withdraw from the city. The bordering kingdom of Piedmont-Sardinia sent troops in order to protect the insurgents and organised a plebiscite that ratified by a huge majority the unification of Lombardy with Piedmont-Sardinia. But just a few months later the Austrians were able to send fresh forces that routed the Piedmontese army at the Battle of Custoza on 24 July and to reassert Austrian control over northern Italy. About ten years later, however, Italian nationalist politicians, officers and intellectuals such as Cavour, Garibaldi and Mazzini were able to gather a huge consensus and to pressure the monarchy to forge an alliance with the new French Empire of Napoleon III in order to defeat Austria and establish a large Italian state in the region. At the Battle of Solferino in 1859 French and Italian troops heavily defeated the Austrians that retreated under the Quadrilateral line. Following this battle, Milan and the rest of Lombardy were incorporated into Piedmont-Sardinia, which then proceeded to annex all the other Italian statlets and proclaim the birth of the Kingdom of Italy on March 17, 1861.