In the years following the emperor's death, generals of the Roman army fought each other for control of the Empire and neglected their duties in preventing invasions. Provincials became victims of frequent raids by foreign tribes, such as the Carpians, Goths, Vandals, and Alamanni, along the Rhine and Danube Rivers in the western part of the empire, as well as attacks from Sassanids in the eastern part of the Empire. Additionally, in 251, the Plague of Cyprian (possibly smallpox) broke out, causing large-scale mortality which may have seriously affected the ability of the Empire to defend itself.