As the Confederates saw it, they seceded BEFORE they took up arms. In your words you acknowledge the secession: ' state that the “seccesh” lost.' That being the case, they were a separate nation, and therefor enemy combatants, not traitors. So which is it, were they secessionists, or traitors? (Because it's one or the other)
That's pretty much the way Lincoln viewed it.
Yes, I would if I were British. The difference is Washington WON! The losers pay the price so yes, Jeff Davis should have been hung.
Except secession at pleasure was not legal. Secession without assent from the Union was not legal. Therefore, they had not seceded.
And after that, they began a war to go along with their treason,which they lost.