[Footnote 126: I cannot agree with Westlake (I. p. 37) that "the space which some writers devote to the distinctions between the different kinds of union between States" is "disproportioned ... to their international importance." Very important questions are connected with these distinctions. The question, for instance, whether a diplomatic envoy sent by Bavaria to this country must be granted the privileges due to a foreign diplomatic envoy depends upon the question whether Bavaria is an International Person in spite of her being a member-State of the German Empire.]
§ 86. A Personal Union is in existence when two Sovereign States and separate International Persons are linked together through the accidental fact that they have the same individual as monarch. Thus a Personal Union existed from 1714 to 1837 between Great Britain and Hanover, from 1815 to 1890 between the Netherlands and Luxemburg, and from 1885 to 1908 between Belgium and the former Congo Free State. At present there is no Personal Union in existence. A Personal Union is not, and is in no point treated as though it were, an International Person, and its two Sovereign member-States remain separate International Persons. Theoretically it is even possible that they make war against each other, although practically this will never occur. If, as sometimes happens, they are represented by one and the same individual as diplomatic envoy, such individual is the envoy of both States at the same time, but not the envoy of the Personal Union.
§ 87. A Real Union[127] is in existence when two Sovereign States are by an international treaty, recognised by other Powers, linked together for ever under the same monarch, so that they make one and the same International Person. A Real Union is not itself a State, but merely a union of two full Sovereign States which together make one single but composite International Person. They form a compound Power, and are by the treaty of union prevented from making war against each other. On the other hand, they cannot make war separately against a foreign Power, nor can war be made against one of them separately. They can enter into separate treaties of commerce, extradition, and the like, but it is always the Union which concludes such treaties for the separate States, as they separately are not International Persons. It is, for instance, Austria-Hungary which concludes an international treaty of extradition between Hungary and a foreign Power. The only Real Union at present in existence outside the German Empire[128] is that of Austria-Hungary, that of Sweden-Norway having been dissolved in 1905.