Ponder this, from the same document:
"In order to justify secession as a constitutional remedy, it must be on the principle that the Federal Government is a mere voluntary association of States, to be dissolved at pleasure by any one of the contracting parties... Such a principle is wholly inconsistent with the history as well as the character of the Federal Constitution. After it was framed with the greatest deliberation and care it was submitted to conventions of the people of the several States for ratification. Its provisions were discussed at length in these bodies, composed of the first men of the country...In that mighty struggle between the first intellects of this or any other country it never occurred to any individual, either among its opponents or advocates, to assert or even to intimate that their efforts were all vain labor, because the moment that any State felt herself aggrieved she might secede from the Union. What a crushing argument would this have proved against those who dreaded that the rights of the States would be endangered by the Constitution! The truth is that it was not until many years after the origin of the Federal Government that such a proposition was first advanced. It was then met and refuted by the conclusive arguments of General Jackson, who in his message of the 16th of January, 1833, transmitting the nullifying ordinance of South Carolina to Congress, employs the following language:"The right of the people of a single State to absolve themselves at will and without the consent of the other States from their most solemn obligations, and hazard the liberties and happiness of the millions composing this Union, can not be acknowledged. Such authority is believed to be utterly repugnant both to the principles upon which the General Government is constituted and to the objects which it is expressly formed to attain.""
New England was making noise about secession during Jefferson’s Presidency, and continued making it until near the end of the war of 1812.
To repeat, in his annual message to Congress, Buchanan stated that "the responsibility and true position of the Executive," bound by solemn oath before God and the country, was "to take care that the laws be faithfully executed."
No human power could absolve the president from this obligation. Buchanan claimed, however, that events over which he had no control "rendered impracticable" the performance of his executive duty.
He referred to executive duty under the Militia Act of 1795, which apparently provided a statutory basis for presidential action in circumstances such as existed in South Carolina. Buchanan argued that the act was effectively nullified by the termination in South Carolina of "the whole machinery of the Federal Government" necessary for law enforcement.
Addressing the broader interpretive problem of the nature of the Union implicated in the action of the South Carolina Convention, Buchanan denied executive responsibility for resolving the constitutional crisis.
He declared: “The Executive has no authority to decide what shall be the relations between the Federal Government and South Carolina. He possesses no power to change the relations heretofore existing between them, much less to acknowledge the independence of that State.”
11/20/1860 President Buchanan’s then Attorney General J. S. Black issued his opinion on this date to support the President. He wrote that neither the President nor Congress had the authority to conduct aggressive armed conflict. He wrote,
“If Congress shall break up the present Union by unconstitutionally putting strife and enmity and armed hostility between different sections of the country, instead of the domestic tranquility which the Constitution was meant to insure, will not all the States be absolved from their Federal obligations?
Despite the perceived effrontery of the secession, Buchanan respected the perpetuation of Constitutional law.
Abraham Lincoln did not allow this respect to supercede his selfish ambitions.