[Ditto]

"launched a military invasion without consent of Congress"

Excuse me? Congress was not in session when the United States was attacked. When they returned, they approved each and every one of the actions Lincoln took under his powers via the Militia Act of 1793. The first significant battle took place after congress gave full authorization for military action.

[Natural Law]

You have assumed a most liberal interpretation of presidential powers. Before the Civil War the prevalent interpretation of the constitution was that the president was only commander in chief once war had been declared. When there was no state of war the military (militia) was under the command of the various state governments. The president as commander in chief was a constitutional convention compromise to assure the individual states that the commander of a single state's militia would not assume command thus making any other states militia's more or less expendable. Since no "war Power Act" was in effect and no Declaration of War existed Lincoln's actions were unconstitutional. (But he never let that get in his way).