authority; but in war there are many ways by which Congress not only have the authority, but are bound to interfere with the institution of slavery in the States.  The existing law prohibiting the importation of slaves into the United States from foreign countries, is itself an interference with the institution of slavery in the States.  It was so considered by the founders of the Constitution of the United States, in which it was stipulated that Congress should not interfere, in that way, with the institution, prior to the year 1808.

During the late war with Great Britain the military and naval commanders of that nation issued proclamations inviting the slaves to repair to their standards, with promises of freedom and of settlement in some of the British colonial establishments.  This, surely, was an interference with the institution of slavery in the States.  By the treaty of peace, Great Britain stipulated to evacuate all the forts and places in the United States, without carrying away any slaves.  If the Government of the United States had no authority to interfere, in any way, with the institution of slavery in the States, they would not have had the authority to require this stipulation.  It is well known that this engagement was not fulfilled by the British naval and military commanders; that, on the contrary, they did carry away all the slaves whom they had induced to join them, and that the British Government inflexibly refused to restore any of them to their masters; that a claim of indemnity was consequently instituted in behalf of the owners of the slaves, and was successfully maintained.  All that series of transactions was an interference by Congress with the institution of slavery in the States in one way—­in the way of protection and support.  It was by the institution of slavery alone that the restitution of slaves enticed by proclamations into the British service could be claimed as property.  But for the institution of slavery, the British commanders could neither have allured them to their standard, nor restored them otherwise than as liberated prisoners of war.  But for the institution of slavery, there could have been no stipulation that they should not be carried away as property, nor any claim of indemnity for the violation of that engagement.

But the war power of Congress over the institution of slavery in the States is yet far more extensive.  Suppose the case of a servile war, complicated, as to some extent it is even now, with an Indian war; suppose Congress were called to raise armies, to supply money from the whole Union, to suppress a servile insurrection:  would they have no authority to interfere with the institution of slavery?  The issue of a servile war may be disastrous.  By war the slave may emancipate himself; it may become necessary for the master to recognize his emancipation by a treaty of peace; can it for an instant be pretended that Congress, in such a contingency, would have no authority to interfere with the institution of slavery, in any way, in the States?  Why, it would be equivalent to saying that Congress have no constitutional authority to make peace.