As a person who was born in the state where the Battle of Gettysburg took place, and as a person who has an earned MA in history, I'd like to add my $0.02 to this discussion.
As some (Dr. Bob in particular) have noted, Abraham Lincoln was not the "Great Emanicaptor" that he's often portrayed as being, and I doubt seriously that it was solely because of any life-long altusitic concern for the people of the black race in the South that he issued it.
First of all, Lincoln was never opposed to the institution of slavery as it existed in the South in 1861. What he was opposed to was the expansion of slavery into the territories in the West. (And there is quite a lot of speculation as to exactly why he was opposed to its expansion there.)
At the outset of the Civil War, the agrarian South had closer trading ties with England than it did with the industrialized North. The South had been one of England's major sources of cotton for her textile mills, and any interruption of this lucrative trading set up would be a cause of great concern for the English merchant classes.
One of the major diplomatic goals of both the Lincoln administration and the Confederate government was to not only woo the English to their side, but also to prevent them from supporting the other side. The Union's blockading of the Confederate port cities seriously interrupted the cotton trade with England, and did much to align the English merchant class with the Confederacy. (BTW, an interesting sidelight to this is the story of the British-built Confederate raider, the C.S.S. Alabama.)
For years in England there'd been a struggle between the far-greater-in-number working class and the smaller, but vastly more influential, merchant class. By the middle of the 19th century, this struggle was finally beginning to bear some small fruit in that the working classes were beginning to have some of their long-standing grievances not only recognized, but also having Parliament act upon these grievances.
Lincoln was quite aware of the fact that if he could do something that would win over the hearts and minds of the English working class, perhaps they, in turn, might be able eventually to exert enough influence in Parliament to at least prevent England from officially recongizing the Confederacy as a separate, autonomous sovereign nation.
Most of the English working class people tended to be sympathetic to the plight of the black people in the South, so, if Lincoln could do something that at least had the trappings of helping the black people in the South, maybe that would make it appear as if he genuinely cared for them. And, in turn, maybe that would keep the English working classes on Lincoln's side.
Thus, we have the conception of the idea of that eventually evolved into what's now called the Emancipation Proclamation.
If one will take the time to read exactly what Lincoln proclaimed in the Emancipation Proclamation, one will quickly see that the only slaves Lincoln proclaimed were free on January 1, 1864, were those slaves residing on the areas still in rebellion against the United States. In other words, only those slaves living outside of the areas that were under the occupation of the Union army on that date were "freed."
Not a single slave in any of the Union border states was freed, nor were any slaves that lived in the areas of the South that were under Union occupation freed, nor were any slaves in the North (and, yes, there were some there too!) freed.
"What slaves Lincoln could free, he didn't! What slaves Lincoln could not free, he did!" was the saying that arose after a very careful examination of the Emancipation Proclamation took place.
What freed all the slaves was not the Emancipation Proclamation. Rather it was the 13th Amendment to the US Constitution that was ratified in December, 1865, some eight months after Lincoln was buried.
And don't think for one moment that there was total sympathy in the North for the Civil War either. There were draft riots in northern cities (esp. New York City) in the 1860's that probably were more deadly than those in the 1960's.
For those interested in the "peace movement" of those years, try looking up what was termed the "Copperheads." It's some rather fascinating reading.
Was Lincoln, therefore, not the one of the "greatest" Presidents we ever had? As was mentioned in a previous post, it all depends on what a person's criteria is for measuring "greatness" (or its lack thereof).
Some other Presidents also come to my mind:
Lincoln's "greatest" general, U. S. Grant, a Republican, would probably be very high on my list as one of the worst ones we had. And handsome Warren G. Harding (the "JFK of his day"), another Republican, would come pretty close to Grant.
Before one labels me as a racist, or whatever other label you wish to sling in my direction, I would suggest that a complete fact check be done about the life and times and real actions of Abraham Lincoln be done.