“The course of events is so rapidly hastening forward that the emergency may soon arise when you may be called upon to decide the momentous question whether you possess the power by force of arms to compel a State to remain in the Union. I should feel myself recreant to my duty were I not to express an opinion on this important subject.
The question fairly stated is, Has the Constitution delegated to Congress the power to coerce a State into submission which is attempting to withdraw or has actually withdrawn from the Confederacy? If answered in the affirmative, it must be on the principle that the power has been conferred upon Congress to declare and to make war against a State.
After much serious reflection I have arrived at the conclusion that no such power has been delegated to Congress or to any other department of the Federal Government. It is manifest upon an inspection of the Constitution that this is not among the specific and enumerated powers granted to Congress, and it is equally apparent that its exercise is not “necessary and proper for carrying into execution” any one of these powers. So far from this power having been delegated to Congress, it was expressly refused by the Convention which framed the Constitution.”
Speech before Congress (3 December 1860).