Scandals over the U.S. military’s domestic surveillance of civilians continue to resurface today. Eyes in the Shadows offers the first exploration of how the monitoring of citizens began just over a century ago. In this new origin story of the U.S. surveillance state, Alexandre Rios-Bordes returns to the First World War, when two modest military intelligence services—the Military Intelligence Division and the Office of Naval Intelligence—began spying on civilians. The book shows why and how this surveillance continued in peacetime, drawing the armed forces into the ongoing monitoring of the population. What processes and practices determine who warrants surveillance? What does it mean for a state to turn against certain citizens and groups and cast them as enemies? To answer these questions, Eyes in the Shadows describes surveillance in the making, immersing readers inside secretive organizations and showing how they operate—from collecting data in the field to writing reports and analyzing threats. The book offers unprecedented insight into the mechanisms of military vigilance, whose shadow still looms over the present.