Speaking of Lincoln, here's what he had to say to Horace Greeley.
I would save the Union. I would save it the shortest way under the Constitution. The sooner the national authority can be restored; the nearer the Union will be "the Union as it was." 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. I shall do less whenever I shall believe what I am doing hurts the cause, and I shall do more whenever I shall believe doing more will help the cause. I shall try to correct errors when shown to be errors; and I shall adopt new views so fast as they shall appear to be true views.
For the whole letter.http://www.abrahamlincolnonline.org/lincoln/speeches/greeley.htm
The first couple of years of the civil war was all about saving the union. Slavery didn't really become the issue until Lincoln issued the Emancipation Proclamation when England was threatening to enter the war on the south's side. It work and the rest is history.
What is strange to me is it always seems someone from the North is always the first to bring up the Civil War as if nothing has changed in 165 or so years. But it is what it is. Besides slavery which certainly played a major role, it was the north demanding that the South sell is cotton and other raw materials only to the factories in the north, rather than to other countries. The north set the price for the cotton and all extra would then be sold by the north and shipped by the north to other countries. There's many other reasons, but they get totally ignored and untaught.
I don't know, perhaps that is for the best. It is said winners write the history and that history is reinvented and changed some by each succeeding generation.
I have an article written by who and where I got it, I don't remember. I saved the article, but it was certainly written by a civil war buff, historian. I'll post it as this one here is long enough.