Andrew J. Pottenger, an instructor in church history at Nazarene Bible College in Colorado Springs, has revised his doctoral dissertation from the University of Manchester (2019) into an interesting book analyzing the epistles of Constantine the Great concerning the Donatist Schism in the western Roman Empire and the Arian Controversy across the eastern Roman world during the twenty-five years in which this emperor ruled after his conversion to Christianity (A.D. 312–337). He offers it as “a contribution to studies of Constantine's reign and association with Christianity” (226) and attempts to highlight the doctrines of imperial power and the techniques of ancient rhetoric the emperor employed in trying to end the organizational and theological divisions of his Christian brethren. The tome is divided into an introduction, six chapters, a conclusion, and contains a full bibliography and a useful index in a packed 273 pages.