A Confederate declaration of war against the United States (May 6, 1861) is a moral absolute.
The rate at which New Jersey & other Northern states gradually abolished slavery in the early 1860s is not.
Back to your well of pretend outrage, I see.
Supreme court says this is when the war started; April 19, 1861
The confederates were apparently late. Lincoln had already been making war on them by the time they declared.