Secessionists themselves said it was all about slavery.
When war started at Fort Sumter that was not about slavery, but rather Confederate "integrity".
Almost immediately slavery became an issue, in the form of "contraband of war" and new Union laws to protect Confederate fugitive slaves.
By the time of Lincoln's preliminary Emancipation Proclamation in September 1862, slavery was very much at issue, second only to Union.
Nothing "revisionist" about that, those are simply the facts.
By the time of Lincoln’s preliminary Emancipation Proclamation in September 1862, slavery was very much at issue, second only to Union.
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Exactly.
For many years leading up to the war, slavery was the number one issue. Once the rebel states left the Union, preservation of the Union became the number one issue and slavery was second. As Lincoln stated in his first inaugural address, the impending war would be about the preservation of the Union and nothing else.
By the time of his second inaugural, victory was all but assured along with the preservation of the Union, so now slavery would be the number one issue again. Lincoln revised history for political reasons.
At no point was war waged against a state for being a slave state. Only states that left the Union had war waged against them. That’s a fact. The war was about preservation of the Union. That’s a fact.
Let’s suppose a rebel state wanted to end its hostilities with the Union during the war, which of these two actions would have worked? Ending slavery and remaining separate, or keeping slavery and rejoining the Union?