This is a heartily welcome book. Gary Dickson, the leading historian of medieval revivalism working in the UK, has been studying the Children's Crusade of 1212 for thirty years. In recent years he has published important accounts of its origins and early stages, but in this book he provides a complete overview of what happened, followed by chapters tracing the development of the legend from the thirteenth-century chroniclers who creatively mixed history with imagination, right up to the present day. Barring the discovery of some breakthrough piece of new evidence, Dickson's book is likely to become authoritative. His scholarly insights and close attention to detail are admirable and he delivers his argument with terrific panache. The author's exuberance and fascination with his subject pay dividends, so that discussion that often cannot help but be technical fairly leaps off the page. Summarising what happened in 1212 remains hazardous, but the gist is as follows. Pentecostal processions organised at Chartres to solicit God's aid for the crisis of the Spanish Reconquista overflowed their liturgical banks and a youth (puer) called Stephen of Cloyes led some thousands of followers to St Denis, whence they were sent home by royal command. Some of the French pueri seem to have made their way (though this can still only be inferred) to Cologne where a second youth called Nicholas also recruited a large following. The association of the devocio with the recovery of Jerusalem and the True Cross (both lost to Saladin in 1187) now became explicit, and Nicholas's host crossed the Alps where the arrival of bands of pueri was recorded at Genoa and Piacenza. After that silence descends. The last trace of the actual movement that we currently possess dates from 1220, when Pope Honorius iii issued an ex-puer called Otto with a dispensation of the crusading vow that he had sworn. The devocio of the pueri left numerous tantalising loose ends. How had it come about? Was it the fruit of devotion or the devil? What happened to its followers? In the 1200s Alberic of Trois-Fontaines, Matthew Paris and Vincent of Beauvais were the main commentators who applied their minds to explaining things, and the elements of nearly all the later myths originated with them: that the pueri were seduced by magicians, betrayed and sold into Muslim slavery, even recruited for the service of the Assassins. In practice the movement's links with ‘official’ crusading were closer than distant critics like Paris liked to believe. Not only was the French devocio triggered by processions promoted for the cause of crusade, but many pueri took the cross, and Otto's need to secure a papal dispensation in 1220 shows that their vows could not simply be set aside. Dickson makes a strong case for the devocio of 1212 as the most spectacular offspring of the long period of wrenching grief felt by the Catholic west for the loss of Jerusalem and the True Cross; one crusade preacher in the immediate aftermath of 1212 pointed to the enthusiasm of the pueri as worthy of emulation. Were the pueri children? On this Dickson hedges his bets. Admittedly the German hosts contained many older people, but even these groups were characterised by contemporaries as movements of pueri: ‘Nearly all the chroniclers single out the youthful pueri as its core group, as well as its most visible and most remarkable element.’ Not a Children's Crusade then, but certainly a youth movement. Its appropriation by the rebels of the '60s, fellow devotees of the impossible, was not so far wide of the mark.