Abraham Lincoln on the reason for war against Southern secession

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 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 save the Union...

~ Abraham Lincoln, public letter to New York Tribune editor Horace Greeley, August 22, 1862