In 'Peter's Rock in Mohammed's Flood, from St. Gregory the Great to St. Leo III,' T. W. Allies provides a comprehensive analysis of the history of the early Church in relation to the expanding Muslim influence. Written in a scholarly yet accessible style, Allies delves into the theological and political intricacies that shaped the Church's response to the Islamic world, from the papacy of St. Gregory the Great to St. Leo III. The book not only offers insights into the historical context of this period but also sheds light on the religious disputes and cultural exchanges that occurred between Christianity and Islam. Allies' thorough research and meticulous attention to detail make this work a valuable resource for scholars and students of theology and history. Through his exploration of the challenges faced by the Church in the face of Islamic expansion, Allies brings to light the enduring influence of early Christian-Muslim interactions on the development of religious thought and interfaith dialogue.