The fact remains, that by the end of the Civil War, and before the 13 Amendment was ratified, 3 million slaves were freed because of the EP as Union troops moved through the South.
The common Lost Cause idiot dodge is that Lincoln did not free 'Northern' slaves. The only 'northern' slaves were those in Maryland, Delaware, Kentucky and Missouri (which no one considered Northern States in those days) and Lincoln had no legal ability to free them under the Constitution since those states were not in rebellion. Lincoln did appeal to those states to free their slaves and Missouri and Maryland did as he requested.
But as Commander in Chief of the Armed forces, he did have the power to order his commanders to seize enemy property (slaves) in areas in rebellion, and dispose of them as necessary -- i.e. freedom.
It was a brilliant stroke.
To say that the Emancipation Proclamation did not free any slaves is a gross untruth. By the end of the civil war, over 3 million were freed with nearly 100,000 of those newly freed slaves serving in the Union Army.
Here is what the London Spectator thought of it [Source: April 1865 by Jay Winik, page 248 paperback version]:
The principle is not that a human being cannot justly own another, but that he cannot own him unless he is loyal to the United States.
Lincoln, while a Congressman, wrote his own fugitive slave law in 1849. It required some governmental authorities to provide means to arrest and return escaped slaves to their owners, but it didn't get passed by Congress. Congress passed a more extensive fugitive slave law the following year. See: Section 5.