Sarah Kreps chronicles the entire history of how America has paid for its wars-and how its methods have changed. Early on, the United States imposed war taxes that both demanded sacrifices from all Americans and served as reminders of their participation. Indeed, thinkers from Immanuel Kant to Adam Smith argued that these reminders were exactly the reason why democracies tended to fight shorter and less costly wars. Bearing these burdens caused the populace to sue for peace when the costs mounted. Leaders in a democracy, responsive to their citizens, would have incentives to heed that opposition and bring wars to as expeditious an end as possible.

Since the Korean War, the United States has increasingly moved away from war taxes. Instead, borrowing-and its comparatively less visible connection with the war-has become a permanent feature of contemporary wars. The move serves leaders well because reducing the apparent burden of war has helped mute public opposition and any decision-making constraints. But by masking accountability, however, the move away from war taxes undermines the basis for democratic restraint in wartime. Contemporary wars have become correspondingly longer and costlier as the public has become disconnected from those burdens. Given the trends identified in Taxing Wars, the recent past-epitomized by our lengthy wars in Afghanistan and Iraq-is likely to be prologue.