[Sidenote: The relation of slavery to the diplomacy of the United States.] Finally, the capture and abduction of negro slaves by the British forces during the War of 1812, and the demand of the slave-holders that the United States Government should secure the restitution of their slaves, or compensation for the loss of them, from the British Government, moved the United States Government to assume its attitude toward slavery in the administration of the international affairs of the country. The cardinal political principle of the slave-holding statesmen, at that period, was that slavery was a "State" matter with which the United States Government had no concern, and in regard to which it had no powers. This appeal to the Government to voice and enforce their demands against Great Britain in respect to their slave property has seemed, therefore, to some of the later and more radical critics of American history to have been a gross inconsistency, and they have represented it as a proof of the insincerity of the slave-holders wherever their pecuniary interests were involved. {59} This criticism is rather taking, but a sound view of the Constitution will hardly support it. In making the United States Government the _exclusive_ organ for dealing with foreign countries, the Constitution impliedly confers upon that Government a protectorate against foreign states over interests which are regulated, internally, only by the powers of the respective Commonwealths of the Union. It is true that this doctrine rests upon a national view of the federal system of government in the United States, a view which the slave-holding statesmen did not later share. From their later particularistic principle of the fundamental character of the Union, such a general protectorate over "State" interests by the United States Government against foreign countries could hardly be inferred from the Constitution. If this principle could be assumed by these critics as having been held at that time by the slave-holding statesmen, their charge of inconsistency, if not of insincerity, would be fairly made out. But such, as we have seen, was not the case. Many of the slave-holding statesmen of 1816 were stronger in the national view of the character of the Union than were the statesmen of New England itself. The United States Government recognized its duty to extend the protection demanded in the case, and it secured from the British Government compensation to the masters for the loss of slave property occasioned by the acts of the British officers during the War.