When does a war begin? When does it end? Start dates and end dates for wars are readily available in textbooks, but are the beginnings and endings really so obvious? Currently, the U.S. claims not to be at war with any nation, yet it is claiming the existence of war as justification for all sorts of policies, from deportation to military occupation of American cities to tariffs. The confusion around the meaning of wartime is not new. It dates back to the U.S. Civil War. Michael Vorenberg, professor of history at Brown University, examines the ways that the Civil War created modern, elastic notions not only of war power but also of war time.