Union military and civilian officials in Pennsylvania rightly viewed the Susquehanna River as a formidable barrier to the Confederate advance to the east. Still, they supplemented the mile-wide river with earthworks along its course. Here, an artist who witnessed the excavation shows workers digging trenches near Wrightsville in eastern York County to provide defenders leverage against an anticipated Confederate offensive to capture the bridge spanning the Susquehanna River between York and Lancaster counties.