The Emancipation Proclamation is an order issued to all segments of the Executive branch (including the Army and Navy) of the United States by President Abraham Lincoln on January 1, 1863, during the American Civil War. It was based on the president's constitutional authority as commander in chief of the armed forces; it was not a law passed by Congress. It proclaimed all those enslaved in Confederate territory to be forever free, and ordered the Army (and all segments of the Executive branch) to treat as free all those enslaved in ten states that were still in rebellion, thus applying to 3.1 million of the 4 million slaves in the U.S. The Proclamation could not be enforced in areas still under rebellion, but as the army took control of Confederate regions, the slaves in those regions were emancipated rather than returned to their masters. From 20,000 to 50,000 former slaves in regions where rebellion had already been subdued were immediately emancipated, and over 3 million more were emancipated as the Union army advanced. The Proclamation did not apply to the five slave states that were not in rebellion, nor to most regions already controlled by the Union army; emancipation there would come after separate state actions and/or the December 1865 ratification of the Thirteenth Amendment, which made slavery illegal everywhere in the U.S. The Proclamation did not compensate the owners, did not itself outlaw slavery, and did not make the ex-slaves (called freedmen) citizens. It made the eradication of slavery an explicit war goal, in addition to the goal of reuniting the Union.
On September 22, 1862, Lincoln had issued a preliminary proclamation that he would order the emancipation of all slaves in any state of the Confederate States of America that did not return to Union control by January 1, 1863. None returned, and the order, signed and issued January 1, 1863, took effect except in locations where the Union had already mostly regained control. The Proclamation outraged white Southerners who envisioned a race war, angered some Northern Democrats, energized anti-slavery forces, and weakened forces in Europe that wanted to intervene to help the Confederacy. It also lifted the spirits of African Americans both in the Southern and Northern States, and led to many slaves escaping their masters and running behind Union lines in order to have their emancipation enforced