briefly explain one example of how lincoln emancipation proclamation change the purpose for the union in the civil war

When the American Civil War (1861-65) began, President Abraham Lincoln carefully framed the conflict as concerning the preservation of the Union rather than the abolition of slavery.

After the qualified Union victory in the Battle of Antietam, Lincoln issued a preliminary proclamation warning that in all states still in rebellion on January 1, 1863, he would declare their slaves "then, thenceforward, and forever free." January 1 came, and with it the final proclamation, which committed the government and armed forces of the United States to liberate the slaves in rebel states