Lincoln stated the war wasn’t about slavery. Many, many times.
The South seceded to preserve slavery. Lincoln fought the South to maintain the Union. Both were express about their respective reasoning.
The war was about slavery, taxes, tariffs, and keeping all of the states in the Union. Lincoln said what he needed to say in order to keep the war effort going. Of course it was about slavery. There were plots and sub plots. A novel has more than one chapter.
But the glue that bottomed out Union desertions was abolitionism.
The question “Lincoln and what army?” Could very well have ended the war had the South freed their slaves...because the North could not have kept a large enough force in the field after the early battles without abolition to galvanize the Union forces and because opposition to slavery kept England from allying with the Confederacy.
Lincoln’s statements were not backed up by the reality of maintaining a force in the field.
Checkmate.
Lincoln didn't start the war. This argument seems similar to President Obama's repeated claim that terrorism isn't about Islam.
And yet Lincoln issued the Emancipation Proclamation! Go figure.
The Confederacy—and its founders—recognized Negro slavery as a central principle upon which their new nation was based. Of that there is no doubt. It's printed in black and white in the Confederate Constitution.
While the U.S. Constitution has a clause that states "No bill of attainder or ex post facto law shall be passed", the Confederate Constitution added a phrase to explicitly protect slavery, and, indeed, recognized it as a Right. Quoting from the Confederate Constitution:
Article I Section 9(4) No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed.So even if the "war" wasn't about slavery, the very existence of the Confedracy categorically was.
So the founders of the Confederacy—who were willing to fight a war to preserve and defend the Confederate Constitution—a Constitution which recognized "the right of property in negro slaves"—apparently disagreed with President Lincoln on that issue.
From Lincoln’s letter to Horace Greeley:
“If there be those who would not save the Union, unless they could at the same time save slavery, I do not agree with them. If there be those who would not save the Union unless they could at the same time destroy slavery, I do not agree with them. My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union.”
It’s about “saving the Union”, not about slavery.