When the Roman historian Tacitus wrote the Germania, a none-too-flattering little book about the ancient Germans, he could not have foreseen that centuries later the Nazis would extol it as a bible and vow to resurrect Germany on its grounds. But the Germania inspired and polarized readers long before the rise of the Third Reich. In this elegant and captivating history, Christopher B. Krebs, a professor of classics at Harvard University, traces the...