Slavery-furiously debated, yet recognized in the Constitution-was a stain on the nation's consciousness since the founding of the Republic. As the country grew, legal battles erupted over the fate of fugitive slaves and the rights of slave-owners to take their property into free states. Nowhere was the issue more sharply drawn than in the nation's capital, where government leaders saw first hand the shame and disgrace of legal slavery and the inherent moral conflict with guarantees in the Declaration of Independence. Decades of agitation for change came to fruition on April 16, 1862, when...