In the first half of the 13th century, the heartland of Muslim Spain, the Guadalquivir valley, fell into Castilian hands, culminating with the conquest of Seville in 1248. Only a coastal strip, from Tarifa to Almanzora, remained in Muslim hands, as the kingdom of Granada. This book is about the the following century, as the Castilian kings repeatedly tried to carry on the Reconquista, and especially to wrest control over the the Strait of Gibraltar, while the Granadine rulers tried to resist them, playing a dangerous game of inviting their Moroccan co-religionists to help keep the Christians at bay while avoiding the fate of earlier Andalusian rulers who had found themselves annexed by previous Moroccan saviours. After the Black Death, both Reconquista ardour and the prospect of Moroccan invasion faded, until the joint Spanish monarchy rediscovered the former in the late 15th century.

On the map, there was not much to show from this century of wars - routinely sanctified as crusades by the papacy and on the Muslim side seen as jihad -, with Tarifa the only permanent Castilian gain of significance, and the Moroccan Marinids eventually handing back to Granada their peninsular outposts to pursue internecine struggles. But it cemented a shift in power: the Marinids were the last Moroccan invaders of the Iberian peninsula, and they were defeated, unlike their Almoravid and Almohad precedessors, who had conquered the southern half of it in the 11th and 12th centuries respectively. In the future, it would be Iberian powers invading Morocco rather than vice versa.

O'Callaghan's book is a strict politico-military history, a chronological narrative with some thematic remarks about military organization, war finance, the ideologies of crusade and jihad, etc. tacked on at the end. Requires some concentration to keep all the people and places mentioned straight, and a tolerably profound interest in the subject to appreciate.