The United States government sent troops to suppress a rebellion. A rebellion caused by several southern states not liking the outcome of an election. These states sent envoys to other states to attempt to get them to join the rebellion. They also captured federal arsenals and other federal properties, before the new president had even been inaugurated. They then fired upon US ships and their rebellion declared war against the US.
Now during the course of this conflict the US government also adopted the goal of ending slavery as a war aim.
The United States sent warships to stop the Southern States effort to be independent of their economic control. Troops came later.
Get it right.
Now during the course of this conflict the US government also adopted the goal of ending slavery as a war aim.
Half way through it. Not at the beginning, where you could rightfully claim it was a matter of principle, but in the middle when it was useful to the effort of suppressing their independence.
Lost in the discussion is the fact that Abraham Lincoln intended very much to keep slavery for the first two years of the war.