The 13th Amendment
President Lincoln issued the Emancipation Proclamation, which states, "all persons held as slaves within any State, or designated part of a State, the people whereof shall then be in rebellion against the United States, shall be then, thenceforward, and forever free." The Emancipation Proclamation did not end slavery, but Lincoln saw that to end slavery, a constitutional amendment will be made.
Prior to the Decision
Before the Civil war in February 1861,Congress had passed a 13th amendment to guarantee the legality and the infinite use of slavery in the (slave) states, rather than to end it.
The promise of this created many problems- and even though the slim fit on the pass on both houses, the Civil War started before it could be sent for ratification.
The 13th amendment we see today was passed during the Civil War years- sadly, it didn't pass easily. Although it was passed in April 1864 by the Senate, (in a vote which was 38 to 6) "*the required two-thirds majority was defeated in the House of Representatives by a vote of 93 to 65." Republicans were mostly the supporters of this, while Democrats were not.
Then, President Abraham Lincoln took great action and became an active role in moving it through in congress. He insisted making the passage a part of the Republican party platform for Presidential elections. He used every skill and trick he known to convince democrats to be supportive of the amendment's passage.
There were still a large amount of people- Southern people, or their representatives that were opposed to freeing the slaves still.
*Source : greatamericanhistory.net
The After-Effect of the 13th Amendment
After the 13th amendment was passed, discrimination against African Americans refused to leave, and they still had limited rights.