Italian nationalism is the nationalism asserts that Italians are a nation and promotes the cultural unity of Italians. It claims that Italians are the ethnic, cultural, and linguistic descendants of the ancient Romans who inhabited the Italian Peninsula for centuries. The origins of Italian nationalism have been traced to the Renaissance. Italian nationalism first arose as a potent political force in the 1830s in the Italian peninsula under the leadership of Giuseppe Mazzini. It served as a cause for Risorgimento in the 1860s to 1870s. Italian nationalism became strong again in World War I with Italian irredentist claims to territories held by Austria-Hungary, and during the era of Italian Fascism.