Constantine the Great died on May 22nd in 337 AD, leaving behind three sons--Constantine II, Constantius II, and Constans--to face the challenge of how to rule the Roman Empire. Division of Empire follows the lives of these brothers, beginning with the death of their father, and traces how they first shared the empire as a triarchy, until one by one the heirs of Constantine fell to the sword. Constantine II was killed by his brother Constans in the civil war of 340, and Constans was murdered by a usurper in 350. Constantius was the last man standing of Constantine's sons, and he reunified the empire under the rule of a sole Augustus, like his father. However, the cracks were already starting to show, and his efforts at reunification would soon prove to be a failure.It is well known that the Roman Empire came to be divided into eastern and western halves in 395, but what is less known is that this was the culmination of a series of smaller fractures, divisions, and then attempts at reunifications that stretched across the fourth century. Division was a process, rather than a singular event, and it is a process that has, until now, received little scholarly attention. William Lewis uses this story of family massacres, civil wars, assassinations, usurpations, and desperate armed struggles for power as a case study for division and an original reappraisal of politics in the mid-fourth century.