President Lincoln issued the Emancipation Proclamation, on January 1, 1863 after the awaited Union victory at the Battle of Antietam. The Proclamation announced all slaves free in the Confederate held states. Lincoln saw the Proclamation as a military necessity. The Proclamation effected slaves differently in the North and South, as it only applied to Confederate controlled slave states, not the slave Border states in the Union. The proclamation itself did not free any slaves because the Union did not have authority in the Confederacy, but was used as a way to broaden the goals of the war to include a moral goal of abolishing slavery and to gain European support. It also gave the Union more soldiers because once blacks heard about the Emancipation Proclamation, they joined the fight with the Union troops. The Emancipation Proclamation would've allowed Southern states to rejoin the Union without giving up slavery.
The people whereof shall then be in rebellion against the United States, shall be then, thenceforward, and forever free.
-Lincoln, Emancipation Proclamation
President Lincoln gave the Gettysburg address in November of 1863 at the dedication of the Gettysburg cemetery, a few months after the Battle of Gettysburg. The speech reminded people that they were fighting to restore the Union and that if they were victorious, the men's lives would not be lost in vain. The speech also stated that the war was a fight for human equality.
Fourscore and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal. - Lincoln, Gettysburg Address