In the post-secession winter of 1861, both Houses of Congress approved a proposed thirteenth amendment to the U.S. Constitution. Three northern States even ratified the proposal before the Civil War intervened. That version of the thirteenth amendment, introduced in the House by Representative Thomas Corwin of Ohio, purported to prohibit any future amendment granting Congress power to interfere with slavery in the States. The Congressional Globe volumes for the winter 1861 legislative session include rich debates about whether the amending power could be used to limit future exercise of that same authority. Those forgotten debates offer significant insights for modern controversies about the exclusivity of, and limitations on, the extraordi...