You didn’t answer the question. The battle cry was “freedom”. Freedom for who?
Yes, the Civil War began because the North was determined to impose its will on the South. And one of the things it wished to impose was that you can’t own human beings. But you go ahead and keep thinking that slavery had nothing to do with it....
To review: the United States constitution enshrined slavery.
If the North fought the war to overthrow slavery, the north was fighting to overthrow the U.S. constitution.