The Emancipation Proclamation was an executive order issued by President Abraham Lincoln on January 1, 1863, as a war measure during the American Civil War, to all segments of the Executive branch (including the Army and Navy) of the United States. It proclaimed the freedom of slaves in the ten states that were still in rebellion, thus applying to 3.1 million of the 4 million slaves in the U.S. at the time. The Proclamation was based on the president's constitutional authority as commander in chief of the armed forces; it was not a law passed by Congress. The Proclamation also ordered that “suitable” persons among those freed could be enrolled into the paid service of United States' forces, and ordered the Union Army (and all segments of the Executive branch) to “recognize and maintain the freedom of” the ex-slaves. 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.
Around 20,000 to 50,000 slaves in regions where rebellion had already been subdued were immediately emancipated. It could not be enforced in areas still under rebellion, but as the Union army took control of Confederate regions, the Proclamation provided the legal framework for freeing more than 3 million more slaves in those regions. Prior to the Proclamation, in accordance with the Fugitive Slave Act of 1850, escaped slaves were either returned to their masters or held in camps as contraband for later return. The Proclamation only applied to slaves in Confederate held lands; it did not apply to those in the five slave states that were not in rebellion, nor to most regions already controlled by the Union army. Emancipation in those regions would come after separate state actions and/or the December 1865 ratification of the Thirteenth Amendment, which made slavery illegal everywhere in the United States of America.