“If slavery was already obsolete, why bother to fight a war to protect the right to maintain it?”
…because my hindsight is sharper than their foresight. Slavery was not “already” obsolete, it was growing obsolete. Gradual historical trends are often unrecognized by those participating in them.
It would also be foolish to fight a war to preserve slavery when the Lincoln administration had not proposed its abolition. Nevertheless, people often fight wars for foolish reasons.
The Confederacy was fighting to maintain its independence against a foreign invasion. The Union was fighting to annex an independent nation and add their territory to its empire. Slavery, as an issue, became a focal point for a number of reasons. The behavior of Northern abolitionists provided a visible illustration of the many traits displayed by Yankees to which Southerners generally objected.
When I was studying American history in twelfth grade, whenever the class was studying one of our wars, the teacher would write three headings on the chalkboard: Political, Social, and Economic. He would then challenge the students to list at least three items under each heading. The items were to name causes for that war. In other words, we were taught that wars are not fought for a single reason, but for a combination of at least nine separate causes in three different categories.
For example, when Desert Storm was deemed “a war for oil,” I recognized that oil was only one of at least three economic causes of that war and there were at least eight other causes under three different categories. If the Civil War was fought over slavery, then slavery would only be one of at least eight other causes under three different categories.
As you have asserted, the civil war did not end slavery. Any decline in the use of slave labor would, therefore, have to be attributed to other causes, for example, its replacement by machine labor.
If you are interested in the Rebs’ perspective I would recommend:
“The South was Right!” by Walter and James Kennedy.
Let me stir the pot some more with this:
It is possible that at some time in the future circumstances will arise that will lead to the reemergence of actual slavery — the officially recognized ownership of people by other people.