There have been two reasons for this book. One is that it tries to shed light on how the crusades, one of the prominent historic features of western Europe, have been perceived by literate and academic commentators over the centuries. It is thus a modest footnote to the history of European civilisation and civility. The second reason is rawer, more demotic, but possibly more important. It is clear that the crusades, or, to be precise, perceptions of the crusades, now matter beyond the shades of academe. An end note of autobiography may illustrate this. In 2006 I published a long book covering the crusades as a whole. It appeared on both sides of the Atlantic. The reaction revealed patterns of engagement and partisanship to rival the most extreme earlier examples of distortion. In general terms, academic commentators and writers in print tended to assess the work – positively and negatively – on its own terms of intellectual and historical merit. Elsewhere, mainly but not exclusively in North America (and not excluding some professional scholars), and especially on the internet, the work was more frequently judged according to what readers perceived as its stance in the great contest of cultures. It was simultaneously praised for depicting Islam as a threatening creed that justified violent opposition to it and condemned for minimising the Islamic threat in the middle ages and, by no leap of imagination, today. Either way, the litmus test was the crudest form of the already crude ‘clash of civilisation’ theory, itself a heated-up version of Cold War propaganda. The debate formed a cocktail of debased Enlightenment positivism, ignorant cultural supremacism and historical illiteracy. The past was imagined as providing a parallel commentary and guide to the present and therefore, in a sense, not past at all. Past and present were being collapsed into each other, the consequent rubble providing the material for convenient tendentious polemic in ways similar to certain strands in contemporary Muslim historiography. Such obsessive First World judgementalism depends on an absence of historic perspective constituting a severe form of cultural solipsism. Given its potential to cause actual present harm, this inspires profound unease. If nothing else, this book has sought to demonstrate that history, the critical study of the evidence that remains from the past, is not fixed. Ultimately, its truth lies in the eye of the beholder. The vision can be shared and agreed widely, it must be directed by evidence, but it is neither absolute nor unchanging. History cannot, therefore, be used as a given certainty, universal fact, immutable interpretation or timeless moral lesson. As the great F. W. Maitland wrote: ‘if history is to do its liberating work, it must be as true to fact as it can possibly make itself; and true to fact it will not be if it begins to think what lessons it can teach’. All serious views on the crusades are contingent and will be challenged and modified in the future as in the past. What none will prove is that the medieval crusades have direct lessons for the modern age. To claim otherwise is to cheat the past and corrupt the present.