There are always economic or moral arguments for specific territorial annexations, Whether these be 'frontier rectification' or schemes of 'closer union' between a stronger power and a weaker.
And in every country there are many individuals who feel personally magnified by an increase in the frontiers of a the state.
Thus nationalism, which is the will of a historically selfconscious people to attain self-government, inclines scarcely perceptibly through irredentism, which is the will to liberate peoples claimed to be of the same nationality, towards imperialism, which is the will to rule other peoples.
No sooner had the Italians freed themselves from Austrian rule than they succeeded to the Austrian claim to dominate South Slavs.
No sooner had the serbs obtained a Yugoslav state than they forfeited the goodwill of their fellow Yugoslavs by establishing in the new state a harsh Serb predominance.
There are many recent instances of the transition from nationalism to irredentism, and of the uncertain distinction between irredentism and imperialism.
Eire claims Northern Ireland, and South Africa claimed the High Commission Territories, as India claimed Portuguese Goa, and Indonesia claimed Western New Guinea, by appeal to some principle other than the wishes of the inhabitants, which were either unknown or hostile to the claim.
Egypt hoped to absorb the Sudan, half of whose population are not Arab. Nkrumah sought a union of West Africa, which would reduce Liberia, with a hundred years experience in self-government, to a position subordinate to Ghana.
The settlers of Southern Rhodesia, in their march towards independence, constructed a Central African Federation of which Nyasaland Source;
Power politics by Martin W. Leicster Univ. press and RILA, Lin 1995, pp. 146-147
What happened to the fate of settlers of southern Rhodesia?