I have copied below all the Sections of the U.S. Constitution that address the questions of Treason and the Powers Denied to the States. I think they go a long way towards explaining why the people who chose to form the Confederate States of America behaved as they did in 1861. What they do not explain or answer is my original question.
Let me ask it again, but this time with a particular specific query: "Why, after First Manassas, did Johnston and Davis not take Jackson's advice and drive straight to capture Washington, D.C.?
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Some further random comments:
Article I Section 6: Rights and Disabilities of Members
The Senators and Representatives shall receive a Compensation for their Services, to be ascertained by Law, and paid out of the Treasury of the United States. They shall in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.
Confederates could not continue as Senators and Representatives of the United States Congress once they had declared their allegiance to the Confederacy. They would have lost their privileges of immunity under Article I Section 6.
Article I Section 10: Powers Denied to the States
No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.
No State shall, without the Consent of the Congress, lay any Imposts or Duties on Imports or Exports, except what may be absolutely necessary for executing it's inspection Laws: and the net Produce of all Duties and Imposts, laid by any State on Imports or Exports, shall be for the Use of the Treasury of the United States; and all such Laws shall be subject to the Revision and Controul of the Congress.
No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State, or with a foreign Power, or engage in War, unless actually invaded, or in such imminent Danger as will not admit of delay.
In the eyes of all sane and sensible Unionists (Ulysses Grant is representative) the United States citizens who fought for the Confederacy were not and never could be considered traitors. They had rebelled against the legal authority of the Constitution, but they had not entered into any Agreement with a foreign Power (Article I Section 6) to levy War against the United States (Article III Section 3).
Article II Section 4
The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.
Article III Section 3
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court.
The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.
Article IV Section 2
The Citizens of each State shall be entitled to all Privileges and Immunities of Citizens in the several States.
A Person charged in any State with Treason, Felony, or other Crime, who shall flee from Justice, and be found in another State, shall on Demand of the executive Authority of the State from which he fled, be delivered up, to be removed to the State having Jurisdiction of the Crime.
The traditional argument that the South was invaded by the North is not to be summarily dismissed as a matter of Constitutional law. The acts of rebellion (hence, the name given to the Congressional Record of the Civil War) - the seizure of Federal property from Customs Houses, Independent Treasuries and Federal armories - all occurred within the boundaries of the Confederate States. The advance of McDowell's army into Prince William County was precisely the circumstance under which a State had the right to engage in War without Congress' approval (Article I Section 10.) The legal authority for the U.S. Army to march anywhere in the United States was questionable in the absence of a formal Declaration of War; and Congress, being full of lawyers, was careful never ever to declare actual war against the Confederacy. When Lincoln arrives in Washington and calls out the militia under Proclamation 80 on April 15, 1861, he does not claim that he has the authority to send the U.S. Army into Virginia. He only asserts the right to defend and reclaim Federal property: "The first service assigned to the forces hereby called forth will probably be to repossess the forts, places, and property which have been seized from the Union." He does not mention a second "service".
www.presidency.ucsb.edu
Lincoln's Proclamation initiating the blockade is equally circumspect; he does not claim any Presidential authority to have the U.S. Army or Navy physically invade a State.
www.presidency.ucsb.edu
When Congress does convene in its Special Session on the 4th of July, it only ratifies the actions Lincoln has taken under the Militia Act of 1795 - i.e. "That whenever the United States shall be invaded, or be in imminent danger of invasion from any foreign nation or Indian tribe, it shall be lawful for the President of the United States to call forth such number of the militia of the state, or states, most convenient to the place of danger, or scene of action, as he may judge necessary to repel such invasion, and to issue his orders for that purpose, to such officer or officers of the militia, as he shall think proper."