In the discussion of the constitutional power of the United States to extend its sovereignty over new territories and to govern such territories when acquired, the fact has been adverted to and relied upon, that the control of the relations of the United States with foreign nations is exclusively vested in the General Government. We have now to examine in detail the consequences which flow from this fact, and to examine into the manner in which the Constitution has provided that the federal powers thus vested are to be exercised.