On January 1, 1863, after three years of a brutal Civil War, President Abraham Lincoln issued the Emancipation Proclamation freeing Confederate slaves.
"Despite this expansive wording, the Emancipation Proclamation was limited in many ways. It applied only to states that had seceded from the Union, leaving slavery untouched in the loyal border states."
The proclamation paved the way for the passage of the 13th Amendment to the Constitution (December 1865), which ended slavery in the United States.
Almost from the beginning of his administration, Lincoln was pressured by abolitionists and radical Republicans to issue an Emancipation Proclamation.