Answer: His main reasoning for going through with the civil war was to preserve the Union, and to unify the United States as a whole also called the Reconstruction Era.
Explanation:
A quote from he when he was asked about his reasons was this, "If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all slaves I would do it." This was the first phase of the war, then it eventually spread to the South where slaves were just hearing of the news. The men of color were practically forcing the army to allow them to enlist as it became a fight for freedom. During it's final part Lincoln's goal had become to try and create a nation not divided by differing ideals, and instead a place where a person is a person.
This is mainly from information that I've gathered, so I'm sorry if I got anything wrong.
Lincoln ran on a political platform opposed to the expansion of slavery in the territories. His election served as the immediate impetus for the outbreak of the Civil War.
