Lincoln's Main Goal here is your answer on this website. - it is a letter that lincoln wrote to greeley.
if people tell you that his goal was to end slavery they are wrong. his goal was to save the union and greeley along with many others pushed the issue that he wasn't doing anything about the slaves, which later came the emancipation proclamation.
sorry the web site i entered did not show up... google ( lincoln's main goal ) and i think it is the first page that shows up click on that. or google horace greeley letter to lincoln. that will help you answer that question for i am studying college level american history