During the 1850s and early 1860s, Iowa, the westernmost free state bordering a slave state, stood as a bulwark of antislavery sentiment while the decades-long struggle over slavery shifted westward. On its southern border lay Missouri, the northernmost slaveholding state. To its west was the Kansas-Nebraska Territory, where proslavery and antislavery militias battled. Missouri slaves fled to Iowa seeking freedom, finding opponents of slavery who risked...