This book is a pleasing contribution to the study of both the crusades in the High Middle Ages and of the medieval papacy. It is refreshing to see a monograph dedicated to such a detailed analysis of papal crusading policy through a biographical as well as historical approach: examining the early life and pontificate of one particularly important medieval pope: Gregory x (1271–6), and his influential role in the history of thirteenth-century crusading. The book achieves two main goals. First, it promotes a more nuanced understanding of the papal call for the ‘Ninth Crusade’ and the role played by the Second Council of Lyons (1272–4) in its planning and implementation. Secondly, the book investigates Gregory x the man: his character, his aims and goals, his devotion to the Holy Land, his relationships with key players on the European scene such as Charles of Anjou, and the extent to which his crusading vision dominated his entire pontificate with the result that, as Baldwin emphasises right at the beginning of his work, ‘The papacy of Gregory x … stood at the very centre of the crusading movement in the later thirteenth century’ (p.1).

The monograph is written in a scholarly yet straightforward style and the arguments put forward are clearly and persuasively articulated. Baldwin emphasises that Gregory pursued an approach to the crusade which was quite different from those in the recent past since, instead of targeting Egypt, so often the focus of crusading endeavours, the aim was to take a land route through Turkey and into Northern Syria with Palestine as its ultimate goal. Baldwin convincingly reasons that with the death of Sultan Baybars in 1272, ‘The possibilities for success of this new strategy – given the massive scale of this crusade, with Mongol and Greek aid – were arguably very strong’ (p. 224), but that with the untimely death of Gregory x in 1276, it was shelved and then rendered obsolete. Indeed, ironically, as Baldwin points out, Gregory's crusading plans made the crusade so papally-dependent that when his successors failed to realise them ‘the opportunity was lost’ (p. 225).

The depth of scholarship in the book is undoubted, with Baldwin showing that he is conversant with and at ease in his handling of a wide range of primary sources: papal registers, royal correspondence, annals, chronicles and cartularies. He is also fully engaged with the works of both older and more recent crusade historians such as Runciman, Throop, Riley-Smith, Lunt, Purcell, Siberry, Housley, Maier and Schein who have made such an invaluable contribution to the study of the crusades. I hope that this book will encourage younger scholars to appreciate the importance of the papacy at the centre of crusading in the High Middle Ages and to combine the study of particular pontificates with the study of particular crusades. We need more such studies.