After having written and released an initial draft of this proclamation in September of 1862, minor changes were made and Lincoln signed it on January 1st, 1863. It declared free the slaves in 10 states not then under Union control, with exemptions specified for areas already under Union control in two states. Lincoln spent the next 100 days preparing the army and the nation for emancipation, while Democrats rallied their voters in the 1862 off-year elections by warning of the threat freed slaves posed to northern whites.
Once the abolition of slavery in the rebel states became a military objective, as Union armies advanced south, more slaves were liberated until all three million of them in Confederate territory were freed. Lincoln's comment on the signing of the Proclamation was: "I never, in my life, felt more certain that I was doing right, than I do in signing this paper." - Summary by Wikipedia and John Greenman