<em>The Emancipation Proclamation.</em>
Explanation:
The Emancipation Proclamation was officially given on January 1, 1863 and sought the end of slavery in the United States by President Abraham Lincoln.
There was a long battle between the Union and the Confederacy with slavery. The Union wanted to abolish slavery, while the Confederate states wanted to keep it, for numerous reasons. Southern states heavily relied on agriculture for wealth, they were not industrialized like the Northern states. The South made money growing cotton, tobacco, and sometimes indigo, this meant that they needed people, in this case slaves, to tend to these crops.
The Emancipation Proclamation did not work everywhere immediately, it took time to free the millions of slaves across the country, but in the end it did work. Lincoln also made sure to time this correctly to make sure he would gain support from the American citizens.
This also lead to the Thirteenth Amendment of the United States Constitution, which abolished slavery for good.
