The Risorgimento's roots lie in 18th-century Italian culture in the works of such people as Ludovico Antonio Muratori, Vittorio Alfieri, and Antonio Genovesi. Italy had not been a single political unit since the fall of the Western Roman Empire in the 5th cent., and from the 16th through the 18th cent. foreign domination or influence was virtually complete. During the French Revolutionary Wars and the period dominated by Napoleon I, the temporary expulsion of Austrian and other repressive regimes and the formation of new states in Italy (see Cisalpine Republic) encouraged hopes for unification.

Secret societies such as the Carbonari appeared and carried on revolutionary activity after the restoration of the old order by the Congress of Vienna (1814–15). The Carbonari engineered uprisings in the Two Sicilies (1820) and in the kingdom of Sardinia (1821). Despite severe reprisals inspired by the Holy Alliance, new uprisings occurred in 1831 in the Papal States, Modena, and Parma. Italian literature of this period, especially the novels of Alessandro Manzoni and the marchese d'Azeglio and the poetry of Ugo Foscolo and Giacomo Leopardi, did much to stimulate Italian nationalism.

The Risorgimento was primarily a movement of the middle class and the nobility; since economic issues were virtually ignored, the peasantry remained indifferent to its ideals. Political activity was carried on by three groups. Giuseppe Mazzini led the radical faction through his secret society Giovine Italia [young Italy], founded in 1831. Its program was republican and anticlerical; it vaguely alluded to social and economic reforms. The conservative and clerical elements among the nationalists generally advocated a federation of Italian states under the presidency of the pope. The moderates—the propertied bourgeoisie and the north Italian promoters of industry—favored unification of Italy under a king of the house of Savoy. This monarch, as it later turned out, was Victor Emmanuel II of Sardinia.

Sardinia assumed the leadership of the Risorgimento in 1848 when the Lombardo-Venetian kingdom rose against Austrian rule and King Charles Albert intervened in favor of the rebels. After initial victories Charles Albert was defeated by the Austrians at Custoza and was forced to sign an armistice and withdraw his forces. Renewing his attack in 1849, he was again defeated by the Austrians at Novara and abdicated in favor of his son, Victor Emmanuel II, who made peace. Meanwhile, revolutions were suppressed in Venice (under Daniele Manin), Parma, Modena, Tuscany, the Two Sicilies, and the Papal States, where a short-lived Roman Republic was proclaimed under the leadership of Mazzini.

The liberal movement gradually coalesced around Victor Emmanuel II and the policies of his minister Camillo Benso di Cavour. Cavour realized that Sardinia could not defeat Austria without foreign aid. He set out to win French support and British sympathy by introducing sweeping social reforms within Sardinia, by inaugurating a free-trade policy, and by joining (1855) the allies in the Crimean War. Emperor Napoleon III met Cavour at Plombières (1858) and promised military aid against Austria.

War broke out in 1859. The French and Sardinians defeated the Austrians at Magenta and caused them to retreat at Solferino. These victories were so costly, however, that Napoleon signed a separate armistice at Villafranca di Verona (ratified by the Treaty of Zürich). Austria retained Venetia, and Sardinia gained only Lombardy. It was also stipulated that Tuscany, Modena, Parma, Bologna, and the Romagna, where revolutionists had organized provisional governments, were to return to their former rulers. This provision was not fulfilled; plebiscites were held (Mar., 1860) in these states, which voted for union with Sardinia. In return for recognizing these plebiscites, Napoleon received Savoy and Nice. The spectacular conquest of the Two Sicilies (1860) by Giuseppe Garibaldi was followed by Sardinia's annexation of Umbria and the Marches. After the Two Sicilies had voted for union with Sardinia, the kingdom of Italy was proclaimed in Mar., 1861.

The remaining territorial objectives of the Risorgimento were Venetia, still in Austria's possession, and Rome and Latium, which the pope was able to retain because of French protection. Through its alliance with Prussia in the Austro-Prussian War of 1866, Italy obtained Venetia. Italy seized the remainder of the papal possessions in 1870 when France withdrew its troops during the Franco-Prussian War. Italian unification was then complete, but unsatisfied nationalism continued to exist in the form of irredentism.