When the enemy was at Frederick, Maryland, Lincoln had made a “promise to myself, and…to my Maker” that “if God gave us the victory in the approaching battle, [I] would consider it an indication of Divine will” in favor of emancipation. Antietam was God’s sign that he “had decided this question in favor of the slaves.” Thus he intended to issue that day the proclamation warning Confederate states that unless they returned to the Union by January 1, 1863, their slaves “shall be then, thenceforward, and forever free.”
As Harold Holzer points out, there had been plenty of hints that something like this was forthcoming. Nevertheless, the proclamation landed like a bombshell on the American public. Republicans praised it, Democrats denounced it, some officers and soldiers in the Union army welcomed it, others including General George B. McClellan privately condemned it, many in the border states reprehended it, Southern whites ridiculed it, and blacks both free and slave thanked God and Abraham Lincoln for this righteous decree.
‘A Bombshell on the American Public’ by James M. McPherson
Photo: President Abraham Lincoln and General George McClellan (second from left) after the Battle of Antietam, October 3, 1862 (Alexander Gardner/Library of Congress)