[418] How far a succession of States takes place in the case of cession of territory has been discussed above, § 84.
Tradition of the ceded Territory.
§ 217. The treaty of cession must be followed by actual tradition of the territory to the new owner State, unless such territory is already occupied by the new owner, as in the case where the cession is the outcome of war and the ceded territory has been during such war in the military occupation of the State to which it is now ceded. But the validity of the cession does not depend upon tradition,[419] the cession being completed by ratification of the treaty of cession, and the capability of the new owner to cede the acquired territory to a third State at once without taking actual possession of it.[420] But of course the new owner State cannot exercise its territorial supremacy thereon until it has taken physical possession of the ceded territory.
[419] This is controversial. Many writers—see, for instance, Rivier, I. p. 203—oppose the opinion presented in the text.
[420] Thus France, to which Austria ceded in 1859 Lombardy, ceded this territory on her part to Sardinia without previously having actually taken possession of it.
Veto of third Powers.
§ 218. As a rule, no third Power has the right of veto with regard to a cession of territory. Exceptionally, however, such right may exist. It may be that a third Power has by a previous treaty acquired a right of pre-emption concerning the ceded territory, or that some early treaty has created another obstacle to the cession, as, for instance, in the case of permanently neutralised parts of a not-permanently neutralised State.[421] And the Powers have certainly the right of veto in case a permanently neutralised State desires to increase its territory by acquiring land through cession from another State.[422] But even where no right of veto exists, a third Power might intervene for political reasons. For there is no duty on the part of third States to acquiesce in such cessions of territory as endanger the balance of power or are otherwise of vital importance.[423] And a strong State will practically always interfere in case a cession of such a kind as menaces its vital interests is agreed upon. Thus, when in 1867 the reigning King of Holland proposed to sell Luxemburg to France, the North German Confederation intervened, and the cession was not effected, but Luxemburg became permanently neutralised.