The Emancipation Proclamation freed slaves as the Union Army liberated areas previously under Confederate control. The slaves in many areas not covered by the EP were already physically freed when the Confederate slaveholders abandoned their plantations and moved south.
Most members of the Union Army strongly supported Lincoln's Emancipation Proclamation and voted for him in huge numbers in 1864 to prove it. They were also very appreciative of the enemy intelligence information supplied by the liberated negros.