Through widespread and relentless surprise attacks and ambushes, Confederate guerrillas drove Union soldiers and their leaders to desperation. Confederate cavalrymen engaged in hit-and-run tactics; autonomous partisan rangers preyed on Federal railroads, telegraph lines, and supply wagons; and civilian bushwhackers waylaid Union pickets. Together, all of these actions persuaded the Union to wage an increasingly punitive war.

Clay Mountcastle presents a new look at the complex nature of guerrilla warfare in the Civil War and the Union Army's calculated response to it. He examines guerrilla...