The Battle of Antietam marked a turning point in the Civil War. Though General McClellan did not pursue Lee as he and the Army of Northern Virginia retreated, the blows inflicted by the Union forces were significant.On the heels of the Union victory, President Abraham Lincoln gave an ultimatum to the South: rejoin the Union by the end of the year, or have your slaves emancipated. None of the rebelling states came back to the Union. Lincoln's Emancipation Proclamation went into effect on January 1, 1863, declaring "all persons held as slaves within any State or designated part of a State, the people whereof shall then be in rebellion against the United States, shall be then, thenceforward, and forever free." The Emancipation Proclamation did not bring slavery to an end, nor did it mean all enslaved people were automatically free. The proclamation only applied to states that were in open rebellion against the Union. It did not extend to the border states of Delaware, Kentucky, Maryland, Missouri, Tennessee, and West Virginia that permitted slavery but had not joined the Confederacy. The proclamation also did not extend to areas of the South that were already under Union control. It was further limited by the fact that emancipation was dependent upon Union victories in the South.
Despite these limitations, the Emancipation Proclamation had a sweeping impact on the Civil War. First, it shifted the focus of the war. For the North, the war became less about the military or politics, and more about morality. Now more than ever, Union soldiers were fighting to end an institution that stripped men and women of their most basic freedoms. This shifted and sharpened focus also discouraged European powers such as France and Great Britain from entering the conflict on the side of the Confederacy, despite their dependence on Southern cotton. Second, the Emancipation Proclamation allowed for the recruitment of black soldiers into the Union army. At the encouragement of black leaders such as Frederick Douglass, black men stepped forward to volunteer, hopeful that their service would guarantee full citizenship in the future. The additional manpower, some 180,000 African Americans between 1863 and the end of the war, helped secure a Union victory over the Confederacy.