Question

Why was the 13 amendment proposed ​

Answer 1

The 13th Amendment to the U.S. Constitution declared that "Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction." Abolishing slavery in the United States, the 13th Amendment was passed by Congress on January 31, 1865, and ratified by the states on December 6, 1865.

Answer 2

It was to try and rebuild Georgia after the civil war.  Lincoln recognized that the Emancipation Proclamation had to be followed by a constitutional amendment to guarantee the abolishment of slavery. The 13th amendment was passed at the end of the Civil War before the Southern states had been restored to the Union and should have easily passed the Congress.