I THINK THE ANSWER IS IN 1863
He passed the emancipation proclamation.
The Emancipation Proclamation
september 22 1862
January 1, 1863
the Emancipation Proclamation
The president signs the proclamation.
Britain would have felt free to help the Confederates, with France likely to follow suit.
Lincoln signed the Emancipation Proclamation which ended slavery.
The Emancipation Proclamation
Yes, he did.
The Emancipation Proclamation
Yes= he signed his full name of Abraham Lincoln.