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.
In a political move it got repackaged in 1863 as a war about freeing the negro.
That was Lincoln's opinion, and he was the Commander-in-Chief.
But that doesn't change the fact that there were coiuntless other Northerners—military and civilian—who adopted a significantly more zealous attitude than Lincoln's comparatively mild one.
Many of those people did think the conflict was about slavery—as the South itself also clearly did, as evidenced by the plethora of references to slavery which were included in the justifications for secession which were promulgated by many Southern states...
You forgot the very end of the letter, perhaps you could post that also?
God set about and put into motion, in his own clarity, the reasons for bringing the Civil War to this nation; the history of this nation since the Civil War proves his genius. As for the men who fought it, schemed through it, made fortunes by it, their reasons were many and muddled and for most, short sighted in scope.
Through this massed dusty bloody confusion of human goodness, competing notions of chivalrous honor, and utter human depravity known as the Civil War, (some aware but only barely, of being herded from above) God drew the warp and weft of his will for this nation into a fabric of his own design. Only God could see the impact of this newly tightly federalized nation(post civil war) upon the world over the next 100 years....two world wars, space travel, advances in science, (ie, the Apollo 9 astronauts who would read Genesis 1 while in orbit about the moon) , a nation strong enough to confront the bolshevist states who surely would have taken over the world, and the rebirth of modern Israel.