The caliph al-Muntasir was the eighth Shi'i Isma'ili Fatimid Caliph, making him both the Isma'ili imam and secular ruler of a vast empire when he came to power in 1036 at the age of seven. However, his political career was one of disaster and decline, leaving the great empire, secular power and wealth he inherited in ruins when he died nearly sixty years later in 1094, on the brink of the Crusades. In Politics and Power in Late Fatimid Egypt, Kirsten Thomson offers an examination of this leader as well as highlighting the context within which he lived: the relations between different empires and between different ethnic and religious groups, sectarianism and the massive contrast between al-Mustansir's secular and religious leadership. Examining a crucial and turbulent chapter that tipped the once glorious Fatimids into decline, this book is vital for all those interested in medieval Islamic history.