“The north.”
That is an interesting comment.
Slavery in the United States was not just constitutional; it was enshrined in the United States Constitution.
If the North was fighting to overthrow slavery with violence as you and others contend, then the North was fighting to violently overthrow the United States Constitution.
At the time of the war, the South claimed the North was fighting against the Constitution. Your claim adds credibility to their view and justifies secession.
“At the time of the war, the South claimed the North was fighting against the Constitution.”
At the time of the war, the South (i.e. the Confederacy) had repudiated the entire Constitution of the United States by withdrawing from the Repulic that the Constitution defined.
They were the ones fighting against the United States Constitution.
Where?
Anyone knows that ending slavery was not the only reason. That is aside from the fact that one of the reasons why the south fought was to preserve slavery.