|Frederick Douglass's descendant (right) with the original Proclamation|
HowStuffWorks provides some background on the document: "The Emancipation Proclamation was a document that officially changed nothing -- Congress had already passed laws outlawing slavery in the rebel states, which was the only territory Lincoln covered in the Proclamation. (Lincoln the politician wanted to keep border-state voters happy.) And the Proclamation took effect on Jan. 1, 1863, two years after the Civil War began -- what took Lincoln so long? Again, politics. He couldn't very well have issued a decree freeing the slaves when the North was losing the war. There would be no way to enforce the Proclamation, thus making it appear a desperate and hollow threat. So Lincoln waited until a big Union win, at Antietam."
More about the Emancipation Proclamation: "Speaking of enforcement, the Proclamation technically freed slaves in another country -- the Confederacy had seceded. So what happened to the slaves in the Union? They had to wait until 1865 for the passage of the slavery-abolishing 13th Amendment, which wasn't officially ratified until after Lincoln was assassinated. But the Emancipation Proclamation must have done something. Otherwise, why would we consider it such an important document? While it didn't technically set anyone free, the Proclamation was part of Lincoln's strategy to demoralize the South, and it worked. Poorer Southern whites resented that they were now fighting a war to protect wealthy plantation owners who were desperate to hold onto their 'property.' And as word of the Proclamation spread, slaves left those plantations en masse. Their exodus even helped turn the tide in the siege of Vicksburg, a vital Union win."