From Blackpast.org:
Following the Union Army victory at Antietam, Maryland on September 17, 1862, President Abraham Lincoln issued a preliminary emancipation proclamation. This document gave the states of the Confederacy until January 1, 1863 to lay down their arms and peaceably reenter the Union, if these states continued their rebellion all slaves in those seceding states were declared free. Fearing the secession of neutral border slaveholding states such as Kentucky, Maryland, and Missouri, Lincoln’s Emancipation Proclamation, excluded those states which left almost one fifth of the four million slaves in bondage. Their freedom would come with the 13th Amendment, ratified in 1865. The Emancipation Proclamation also allowed freedmen to enlist into the Union Army. This provision struck a series blow to the economic structure of the seceding states as many black slaves labored for the Confederate Army or were engaged in vital agricultural or This Proclamation was not without its criticismindustrial production for the Confederacy.
This Proclamation was not without its criticism as as slavery and the issue of black freedom and equality were highly divisive issues even in the North. Confederate leaders threatened to summarily kill any black man they captured wearing a Union uniform. Anti-War Northern Democrats, who often attacked Lincoln’s policies, claimed that this one would irreparably harm the nation. Many northerners felt that freedmen would flock to the north and compete with white workers. That fear helped fuel the New York Draft Riots of 1863. Others feared the Proclamation would generate a race war between blacks and whites in the Confederacy.
More here. (Note: One post throughout February will be dedicated to Black History Month.)