The answer is The Emancipation Proclamation. It was issued by President Abraham Lincoln on January 1, 1863, as the country entered the third year of the Civil War. He declared that "all persons held as slaves … shall be then, thenceforward, and forever free"—but it applied only to states designated as being in rebellion, not to the slave-holding border states of Delaware, Kentucky, Maryland, and Missouri or to areas of the Confederacy that had already come under Union control.
