Why did Britain invade Iraq in March 2003? Debate around Iraq focuses often on illegality, lies, incompetence, or the personal psychology of Tony Blair. ‘Operation Telic’ is often presented as a war of bad faith, waged by elites who had unspeakable secret motives. Beyond fixations with ‘dodgy dossiers’, the flaws of individual leaders, or intelligence failure, Iraq was a real ideological crusade, made by people who were true believers. Deploying primary documents and retrospective testimonies of participants, Blunder reconstructs the assumptions underlying decisions, the policy ‘world’ that participants inhabited 2001–2003, and the way decisions were made. Contrary to much of the existing literature, this book puts ideas in the centre of the story. As the book argues, Britain’s war in Iraq was caused by bad ideas that were dogmatically and widely held. Three ideas in particular formed the war’s intellectual foundations: the notion of the undeterrable, fanatical rogue state; the vision that the West’s path to security is to break and remake states; and the conceit that by paying the ‘blood price’, Britain could secure influence in Washington DC. These issues matter, because although the Iraq War happened years ago, it is still with us. As well as its severe consequences for regional and international security, the ideas that powered the war persist in Western security debate. If all wars are fought twice, first on the battlefield and the second time in memory, this book enters the battle over what Iraq means now, and what we should learn.