Even as scandals over the US military’s domestic surveillance of civilians continue to surface today, Eyes in the Shadows reveals how this monitoring of citizens began more than a century ago. In this new origin story of the US surveillance state, Alexandre Rios-Bordes returns to the First World War, when two modest intelligence services—the Military Intelligence Division and the Office of Naval Intelligence—began spying on civilians. The book shows why and how this practice 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 field data to writing reports and analyzing threats. The book offers unprecedented insight into the mechanisms of military vigilance, the shadow of which still looms over the present.