Book excerpt: During the 1840s and 1850s, a dangerous ferment afflicted the North-South border region, pitting the slave states of Maryland, Virginia, Kentucky, and Missouri against the free states of New Jersey, Pennsylvania, Ohio, Indiana, and Illinois. Aspects of this struggle--the underground railroad, enforcement of the fugitive slave laws, mob actions, and sectional politics--are well known as parts of other stories. Here, Stanley Harrold explores the border struggle itself, the dramatic incidents that comprised it, and its role in the complex dynamics leading to the Civil War.