1862: President Abraham Lincoln issued the Emancipation Proclamation

On this day in 1862, President Lincoln issued The Emancipation Proclamation:  

In July 1862, Lincoln informed his cabinet that he would issue an emancipation proclamation but that it would exempt the so-called border states, which had slaveholders but remained loyal to the Union. His cabinet persuaded him not to make the announcement until after a Union victory. Lincoln’s opportunity came following the Union win at the Battle of Antietam in September 1862. 
On September 22, the president announced that slaves in areas still in rebellion within 100 days would be free.
On January 1, 1863, Lincoln issued the final Emancipation Proclamation, which declared “that all persons held as slaves” within the rebel states “are, and henceforward shall be free.” The proclamation also called for the recruitment and establishment of black military units among the Union forces. An estimated 180,000 African Americans went on to serve in the army, while another 18,000 served in the navy.
After the Emancipation Proclamation, backing the Confederacy was seen as favoring slavery. It became impossible for anti-slavery nations such as Great Britain and France, who had been friendly to the Confederacy, to get involved on behalf of the South. The proclamation also unified and strengthened Lincoln’s party, the Republicans, helping them stay in power for the next two decades.

It was a controversial move.    President Lincoln then fought for the 13th Amendment that ended slavery in the US in 1865.