Early in the Civil War, to keep the border states in the Union, Lincoln resisted the demands of radical Republicans to free the slaves. Military commanders and Congress, though, whittled away at slavery on their own. The Confiscation Acts of 1861 and 1862 allowed captured or runaway slaves who had been in use by the Confederacy to support the Union effort instead and gave real freedom to slaves belonging to anyone actively participating in the war against the Union.
Lincoln proposed a plan that would gradually abolish slavery in the United States, but he soon realized that immediate action was necessary, both on military and moral grounds. He delivered the Preliminary Emancipation Proclamation on September 22, 1862, after Union success at Antietam, and the formal Emancipation Proclamation on January 1, 1863. The Emancipation Proclamation ostensibly freed all slaves in the rebelling Confederate states; it did not abolish slavery in the Union states in which it was still legal.
Although the Emancipation Proclamation didn't actually free any slaves, it did have a huge impact on the war effort:
- Southern slaves knew that real freedom, as opposed to the ideal of freedom, awaited them in the Union, giving them greater cause to flee north or to undermine Confederate strategies.
- The Emancipation Proclamation also guaranteed that African Americans — both runaway southern slaves and northern freemen — would be allowed to join the Union army and navy and fight against the Confederacy. Almost 200,000 African Americans, mostly former slaves, contributed to the Union war effort; around 37,000 of those gave their lives for it.
- The Emancipation Proclamation redefined the purpose of the war. What had begun as a test of whether a state could withdraw from the Union became an ethical battle over the future of slavery in the United States.
Slavery wasn't completely abolished in the United States until the Thirteenth Amendment was ratified in 1865.