Answer:
The Unification of Italy was the historical process that throughout the nineteenth century led to the union of the various states into which the Italian peninsula was divided, mostly linked to dynasties considered "non-Italian" such as the Habsburgs or the Bourbons .
Historians like Benedetto Croce see the process as the conclusion of the unifying trend initiated in the Italian Renaissance, interrupted by the French and Spanish invasions of 16th-century Italy. This national renaissance reached, in the nineteenth century, all regions inhabited by Italian people, from Sicily to the Alps, and, by 1919-1920 the irredentant Italy, that is Trentino, Trieste, Istria and the city of Zara (Zadar en cr.) in Dalmatia.
In any case, the process was finally channeled by the house of Savoy, reigning in Piedmont-Sardinia (notably by the prime minister count of Cavour), to the detriment of other "republican" interventions of notable characters (Mazzini, Garibaldi) throughout of complicated vicissitudes linked to the European equilibrium (interventions of France and the Empire of Austria), which culminated in the incorporation of Rome and Lazio, the last redoubts of the Papal States in 1870. The new Kingdom of Italy continued the claim of border territories, especially with the Austro-Hungarian Empire (Trieste / Istria / Dalmatia and Trentino), which were partially resolved in 1919 after World War I (Treaty of Saint-Germain-en-Laye with the Fiume expedition of Gabriele D'Annunzio).
