Short answers, pulled from the story.
The phrase Italia irredenta means unredeemed Italy and emerged in the late 19th century to describe Italian territories still held by Austria-Hungary. By 1878, Italian nationalists began claiming regions like Trentino, Trieste, Gorizia, Istria, Fiume, and Dalmatia as part of their national identity.
Political scientist Benyamin Neuberger insists a pre-existing state is necessary for true irredentism. He argues that non-state actors attempting to change borders without an existing parent state do not qualify under his definition.
Nazi Germany's annexation of the Sudetenland occurred in 1938 and represents the typical form where one state absorbs part of another. This event illustrates how states with homogenous ethnic populations are more likely to pursue territorial expansion because internal power balances remain stable.
Russia's annexation of Crimea occurred in March 2014 when Moscow alleged Ukrainian government failed to uphold rights of ethnic Russians. Sixty years earlier in 1954, both nations had been part of the Soviet Union when Crimea transferred from Russia to Ukraine.
Argentina's invasion of the Falkland Islands in 1982 ended after two months despite analysts considering the Argentine military position unassailable. The war concluded with UK victory even though Argentina did not officially declare cessation until 1989.