Italian irredentism (irredentismo italiano) was a political movement during the late nineteenth and early twentieth centuries in Italy with irredentist goals which promoted the unification of geographic areas in which indigenous peoples were considered to be ethnic Italians. At the beginning, the movement promoted the annexation to Italy of territories where Italians formed the absolute majority of the population, but retained by the Austrian Empire after the Third Italian War of Independence in 1866. During World War One the main "irredent lands" (terre irredente) were considered to be the provinces of Trento and Trieste and, in a narrow sense, irredentists referred to the Italian patriots living in these two areas.
The term was later expanded to also include multilingual and multiethnic areas, where Italians were a relative majority or a substantial minority, within the northern Italian region encompassed by the Alps, with German, Italian, Slovene, Croatian, Ladin and Istro-Romanian population, such as South Tyrol, Istria, Gorizia and Gradisca and part of Dalmatia. The claims were further extended also to the city of Fiume, Corsica, the island of Malta, the County of Nice and Italian Switzerland.
During the Risorgimento in 1860, the Prime Minister of the Kingdom of Sardinia Camillo Benso, Count of Cavour, who was leading the unification effort, faced the view of French Emperor Napoleon III who indicated that France would support militarily the Italian unification provided that France was given Nice and Savoy that were held by Sardinia, as France did not want a powerful state having control of the passages of the Alps. As a result, Sardinia ceded Nice and Savoy to France in exchange for France accepting the sending of troops to help the unification of Italy.
To avoid confusion and in line with convention, this article uses modern English place names throughout. However, most places have alternative names in Italian. See List of Italian place names in Dalmatia.