If you admit that the Confederacy was “conquered”, then it was properly “The War of Yankee Agression”.
I will counter your question with my own: “When has this country ever fought a war purely for conquest?” If your answer is “Never”, you give lie to your original question. If you answer every time we go to war, you are wrong for we have no “possessions” save those who won’t go away. And if you answer only to preserve the Union, then what good is a union of the coerced.
Deo vindice