He was simplywaiting for a Union victory. It happened at Antietam (Sharpsburg).
Lincoln announced the Emancipation Proclamation after the Union victory at the Battle of Antietam.
The Emancipation Proclamation was signed by Abraham Lincoln January 1, 1863. It had been previously announced and published in September 1862, shortly after the Battle of Antietam.
After, it allowed Lincoln to issue the Emancipation Proclamation
The outcome of the battle of Antietam motivated Lincoln to release the Emancipation proclamation.
Until Antietam everyone thought that the North might actually loose the war. Antietam was just the victory Lincoln had been waiting for allowing him to issue the Emancipation Proclamation.
The Battle of Antietam, September 17th, 1862.
While it wasn't immediately following, the Battle of Antietam and the Union victory there gave President Lincoln the push to issue the proclamation. The Emancipation Proclamation was issued on January 1, 1863.
Lincoln waited until after the Battle of Antietam to issue the Emancipation Proclamation because he wanted to wait for a Union victory to give the proclamation more credibility and show that the Union was in a stronger position.
Lincoln issued the Emancipation Proclamation after the Battle of Antietam to shift the focus of the Civil War from just preserving the Union to also include the abolition of slavery. The victory at Antietam provided the political momentum and military opportunity for Lincoln to make this significant decision.
Earlier in the begining of the battle Antietam, Lincoln felt that making emancipation the main goal of the war might divid the north.
The result or outcome of the Battle of Antietam(in which Union Army won) was freeing of slaves after Lincoln's Emancipation Proclamation.
Antietam