Final answer:
The quote is not attributed to a known source. The 13th Amendment abolished slavery and involuntary servitude except as punishment for a crime, and while conscription was used during the Civil War, it was not considered a violation of the amendment.
Step-by-step explanation:
The quote 'Conscription is slavery, plain and simple. And it was made illegal under the 13th amendment, which prohibits involuntary servitude' does not appear to be attributed to a specific individual within the provided information or widely recognized historical sources. The 13th Amendment, which was passed by Congress in early 1865 and ratified by the end of that year, abolished slavery and involuntary servitude except as punishment for a crime. However, the use of conscription during the Civil War, known as the Conscription Act in the Confederacy and the Enrollment Act in the Union, was not considered a breach of the amendment. Exemptions and substitutions in the draft made it seem like 'a rich man's war but a poor man's fight', underscoring the inequalities inherent in the conscription system.