There are a few elements missing in this discussion. First, Congress (and the President) did have the right to stop the secession. It is covered in the Constitution under two sections:
Section 8 – The Powers of Congress:
“To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;”Section 10 - Powers prohibited of States“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.” The states that seceded had their own troops and their own navy. And, before you start to speculate outside of your ken, I am a native Virginian.
Additionally, Lincoln did have the right to suspend Habeas Corpus under Section 9 of the Constitution:“The privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.”
Finally, y'all seem to have left out one overriding concept for the Southern States throughout this entire discussion, and it is a concept that is still being forgotten by the current president: states rights. The 10th Amendment specifically states: ”Powers of the States and People. The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.”
Chew on that for a while. . .