What did Abraham Lincoln hope to achieve by issuing the Emancipation Proclamation?

It is a challenge to enter Lincoln's mind and probe to see all the different hopes and angles to his issuing of the Emancipation Proclamation.  We do know that one of the hopes of the document was to end slavery.  It was an active step in the abolition of slavery, and while the exact results of it could be debatable in terms of where it reached and where it did not measure seismic impact, one can say that the single act of a United States government actively defining slavery and slave ownership as something against the law is a powerful and compelling step.  Another hope of the document was to galvanize the war effort.  The Emancipation Proclamation was the first government produced document during the war that sought to conceive of the conflict in moral terms.  At the outset of the war, the belief was that the South had no right to secede and the war was fought to keep the nation together.  The issue of slavery had not been introduced into the discourse.  However, over time, the North had been able to create an effort that actually could materialize into victory.  With this in mind, Lincoln's Emancipation made it abundantly clear that the tactical notion of keeping the nation together had given way to a moral imperative that the war was being fought for something larger than politics or tactics.  The Emancipation Proclamation helped abolitionists galvanize behind the war effort, and also served to inspire slaves and former slaves to understand how they fit into the North's designs.  Giving hope to those who had none, the document cast the South as not merely wrong, but rather "evil."  While its impact on militaristic grounds is negligible, and probably did not result in a single batter being won, the Emancipation Proclamation played a very large role in the North winning the Civil War.