The country was at war.
He did the right thing.
Treason was the reason for the season.
Indeed, it was.
Article III, Section 3 states, "Treason against the United States, shall consist only in
levying War against them, or in adhering to their Enemies, giving them Aid and Comfort."
Abraham Lincoln asserted that South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana, and Texas were still states in the Union and yet he "levied war against them."
He engaged in the flimsy excuse of calling them, "
combinations too powerful to be suppressed by the ordinary course of judicial proceedings" but when they occupied state capitals, federal forces overthrew the state government, not the "combinations."
There was indeed treason going on in 1861. It was treason by Abraham Lincoln and everyone who followed his orders to levy war against states Lincoln himself asserted were still in the Union..
On the other hand,
Art. IV, Section 4 states, "The United States
shall guarantee to every State in this Union a Republican Form of Government, [not
may, but
shall. Guaranteeing a republican form of government is a positive duty, and not a military government, but a republican form.]
"The United States... shall protect each of them against Invasion; and
on Application of the Legislature, or of the Executive (when the Legislature cannot be convened) against domestic Violence."
If there is a foreign invasion, the United States shall protect the states, but in the case of "domestic violence," it requires a request from the legislature or the governor for the United States to intervene. None of those seceding states requested federal intervention.