They did not go to war to end slavery either. Show me one state that sent troops for the purpose of freeing the slaves. Show me one quote of Abe Lincoln's stating he was going to war to free the slaves. He states his only purpose is to save the Union.
Shall I post some Lincoln quotes? I have two websites that you may not agree with but they source all quotations.
If you want to start a search on your own, here is a link to the Collected works of Abrham Lincoln. Use the search term "negro", doing a simple search, and see what you find.
http://quod.lib.umich.edu/l/lincoln/
GP