One of the major outcomes of the North winning the U.S. Civil War was the abolition of Slavery.
After the war broke out, through a legal maneuver the Union general Benjamin Butler, stated that any slave who came into "Union possession" were considered contraband of war, and because of this, they were not subject to be returned to their original owners, the Confederates. And as a result the word was spread and soon many slaves sought refuge in the Union territory in order to be declared as "contraband".
Later general Butler's interpretation was reinforced by the Confiscation Act of 1861, which stated that any Confederate military's property, including slaves, could be confiscated by Union forces.
And finally, due to the Emancipation Proclamation issued on January 1st, 1863, in a single stroke over 3 million slaves in designated areas of the Confederacy changed their legal status and were recognized by the U.S. government as free people.
