The victorious Civil War General Ulysses S. Grant was the Republicans’ unanimous choice for president in 1868. As in so many other presidential campaigns, the Democrats made race the centerpiece of their appeal to the American people. They nominated former New York governor Horatio Seymour and ran him on a platform calling for the “immediate restoration of all States to their rights in the Union under the Constitution,” amnesty for all former Confederates, and “the regulation of the elective franchise in the States by their citizens.” That last point meant the right of white Southerners, chiefly former slaveholders and all...