And they would be right, since the purpose at the end of a war is more important than at the beginning.
Let me give you an example from American history. The Mexican War, probably the most dishonest in US history, was purportedly entered into by Polk to repel Mexican invasion of US territory. (In fact, it is questionable whether the clash in question even occurred on US soil.)
But as US forces succeeded, the goal of the war changed, with progressively more and more of Mexico planned to annexation. First NM and then CA. By the end of the war, Polk and his ilk had determined to annex most if not all of Mexico. He even fired his treaty negotiator, who ignored the firing and produced the somewhat more moderate treaty that ended the war.
But the point is that "what the Mexican War was about" changed with the ebb and flow of the war. Public goals at the start were quite different from those at the end. Same with WBTS.
Wars, particularly civil wars, are like revolutions. Those who start a war almost never wind up where they intended.
Disagree. They would be correct in stating that it became the ultimate stated justification for the slaughter, but you must know that, from the Union perspective, it was about territory. You may believe the stated purpose at the end is more important, but if that is the case then why take issue with my brief statement about the context of the beginning of the war? What the war may have ultimately become in the minds of some is wholly irrelevant to what drove events early on. Suppose the southern states had seceded for other than reasons of perceived economic necessity, slavery having been obviated by technology or an economic shift. You think Lincoln would have said “Aw shucks, well at least they don’t hold slaves anymore.” and waved goodbye and wished them well? Of course not.