Among the many deadly innovations that were first deployed on the battlefields of World War I, none was as terrifying - or notorious - as poison gas. First used by the Germans on April 22, 1915, gas was instantly seen as a new way of fighting war, an indication that total warfare was here, and would be far more devastating and cruel than anyone had imagined. This book investigates the effects of chlorine gas at all levels, from its effects on individual soldiers to its impact on combat operations and tactics to its eventual role in the push to codify rules of warfare. Gathering eleven historians and experts on chemical weapons, Innocence Slaughtered puts WWI's cruelest innovation into its historical, industrial, and social context.