In Georgia the largest slave holding percentage in the South less than 15% of the population owned slaves. Most people never owned a slave. They were fighting for states rights and to repel an invading military force.
The South was not trying to overthrow the United States govt or take and occupy Northern territory or the US capital. They were trying to withdraw from the social compact called the Constitution which they had every right to do. That right was taken from them at the point of a gun. It does not mean they didn’t have that right and still have it today.
Lincoln didn’t give a rats azz about slavery until the war was not going well and the general mood of the Northern population was against continuing the conflict. He needed something to whip up sentiment so he could continue to raise money and keep the war going. So he used the abolitionists and slavery to advance his agenda. Its called politics.
When I was growing up we had one car in my father's name. So strictly speaking only 25% of the family owned a car but 100% drew benefit from it.
Likewise with slavery. Only 15% of Georgians may have owned slaves but add their wives to the equation and about 30% of the population benefited from those slaves. Add children and possibly half the people directly benefited from slavery.
They were fighting for states rights and to repel an invading military force.
State's right to do what?
Lincoln didn’t give a rats azz about slavery until the war was not going well...
Debatable, but one cannot deny that the South certainly gave a rat's azz about slavery from day one.