From Vietnam to Syria, politicians, commentators and journalists have argued both for and against intervention, whether military or humanitarian. Simon Jenkins here presents a provocative and wide-ranging survey of the history of—and the arguments surrounding—intervention in Kosovo, Afghanistan, Iraq, Libya and Syria. Do nations intervene because of right and wrong? Is Western intervention simply a form of ‘imperialism-lite’? When is intervention justified? Jenkins traces the evolution of ‘liberal interventionism’ and shows that scepticism towards it came and comes not just from a growing perception of its failure. Instead, he argues that the past few decades can be characterised as an age of intervention, displaying worrying signs of merely laundering old-fashioned western imperialism and bordering at times on a crusader complex. In the face of recent conflicts—particularly in the Ukraine and with the rise of Islamic State—what can we learn from the miscalculations, mistakes and mendacity of ‘the age of intervention’?