Ohio’s Rufus P. Ranney embodied many of the most intriguing social and political tensions of his time. He was an anticorporate campaigner who became John D. Rockefeller’s favorite lawyer. A student and law partner of abolitionist Benjamin F. Wade, Ranney acquired an antislavery reputation and recruited troops for the Union army; but as a Democratic candidate for governor he denied the power of Congress to restrict slavery in the territories, and during the Civil War and...