irredentism (ĬrĬden´tĬzəm), originally, the Italian nationalist movement for the annexation to Italy of territories—Italia irredenta [unredeemed Italy]—inhabited by an Italian majority but retained by Austria after 1866. These included the Trentino, Trieste, Istria, Fiume, and parts of Dalmatia. Agitation took place both inside Austria-Hungary and in Italy itself. The liberation of Italia irredenta was perhaps the strongest motive for the entry of Italy into World War I. The Treaty of Versailles (1919) satisfied most of the irredentist claims. The term irredentism has, by extension, been applied to nationalist agitation in other countries, based on historical, ethnic, and geographical reasons, for the incorporation of territories under foreign rule. Irredentism is thus closely connected with nationalism and with minority problems.