The Thirteenth Amendment is one of three Civil War amendments (alongside 14th and 15th amendments); the amendment formally abolished slavery in the United States. It was proposed by Congress on January 31st, 1865 and declared ratified on December 18, 1865 at the end of the American Civil War. It was important because for the first time, the issue of slavery was resolved.
President Abraham Lincoln declared freedom for more than three-fourth of the American slave through the Emancipation Proclamation. The Emancipation Proclamation, although very significant, was limited. It only declared slaves free only in the rebel states (Confederacy) and not in the four loyal slave states (Maryland, West Virginia, and East Tennessee).