Success in war has always been difficult to measure. What is judged successful by military leaders may not be judged so by political leadership, nor by the wider public, at least in a Western-style democracy. The public is generally inclined to applaud military victory, but it instinctively reserves the right to ask afterwards: Was it really worth it? In Political Victory, Brian Crozier looks at modern wars involving democracies to evaluate victory and defeat by the success or failure of political outcomes.

Crozier begins with the two world wars, where in both cases the German...