The period between the two world wars of the twentieth century was one of the most challenging in the history of war. In anticipation of another conflict, military planners and civilian thinkers struggled after 1918 with the painful implications of World War I. Given its scope, the wholesale mobilisation of civilian populations and the targets of civilians via blockades and strategic bombing, many observers regarded this titanic conflict as a 'total war'. They also concluded that any future conflict would bear the same hallmarks; and they planned accordingly. The essays in this collection, the fourth in a series on the problem of total war, examine the inter-war period. They explore the consequences of World War I, the intellectual efforts to analyse this conflict's military significance, the attempts to plan for another general war and several episodes in the 1930s that portended the war that erupted in 1939.