In this small gem of a book, William Jordan shows how Louis ix of France brought converts from Islam back with him from the Holy Land and resettled them in France. Missionary efforts to convert Muslims to Christianity, Jordan affirms, were an essential part of Louis's vision of crusade. Various thirteenth-century European Christian writers and kings dreamed that Christian armies’ victories over Muslims could lead to the conversion of Muslim princes to Christianity. This would in turn make way for the massive conversion of their subjects. As Jordan shows, Louis took concrete steps to realise this dream, despite, and in the wake of, his crushing military defeat in Egypt. In Acre, where he resided after having been freed from captivity in Egypt, he engaged Dominican friars to accompany him in order to preach to Muslims. He minted coins with Christian inscriptions in Arabic, marked with the cross, as another way to spread his Christian message. He bought slaves and had them baptised. He offered gifts (including, probably, some of his freshly minted coins) to Muslims who accepted baptism. Some chroniclers speak of Muslims flocking to Acre to accept baptism; others mention the conversion of prominent Muslim military leaders. Is this all just ‘a house of straw inspired by a hagiographical conceit’ (p. 55), as earlier historians thought? The chronicler Geoffrey of Beaulieu said that the king welcomed these converts, provided for them, brought them back to France and accorded them an annual allowance. Earlier historians dismissed or ignored this assertion. Jordan decided to take it seriously, and to look for evidence of these converts in France. And he found it in abundance.

Louis returned to France in 1254. In the years between 1253 and 1255, various fiscal and administrative documents testify to the settlement of converts from Islam in towns and villages across Northern France. Jordan estimates that there may have been roughly 1,500 immigrants. The crown provided them with lodging, winter clothing and a regular allowance for expenses. These living stipends were accorded for life to the immigrants, and fiscal records show payments made for them until at least 1305 (when the youngest children among the immigrants would have been over fifty). Royal emissaries (whom Jordan calls ‘ombudsmen’) were designated to verify that the needs of the immigrants were being met and that they received just treatment from local and royal officials.

While the chroniclers had emphasised the conversion of prominent Muslim military leaders, the documentation tells another story: most of the immigrants were of modest means, many of them were women (probably widows in many cases) with dependent children. A few of them received special treatment: a certain Dreux of Paris was granted the substantial sum of ten pounds for his wedding, enough to throw a sumptuous party. Dreux served as a royal emissary in liaison with converts across northern France, whose concerns he could understand and address and to whom he might serve as a model of successful integration. Gobertus Sarraceni de Lauduno, Gobert the Saracen from Laon, collected revenues for the crown and in 1287 attained the rank of castellan. Others were less fortunate and less successful at integrating. Some disappeared from their adopted villages, perhaps taking their stipends and using them to try to buy passage back to the Levant. As most of these immigrants adapted to life in France, Louis set off on another crusade, to Tunis, lured (at least according to some of the sources) by the prospect of converting the Hafsid emir al-Mustansir.

The records that Jordan analyses had been overlooked or misunderstood by previous historians; many (including Jordan himself, as he acknowledges) had assumed that the converts mentioned in these sources must have been converted Jews. Jordan carefully tracks down and puts together the records of the crown's financial outlays and legal and administrative measures for these immigrant converts. This painstaking detective work provides a fascinating study that will be of great interest to historians of the crusade and of the French crown.