The Plague of Cyprian was a pandemic which afflicted the Roman Empire from about AD 249 to 262, or 251/2 to 270. The plague is thought to have caused widespread manpower shortages for food production and the Roman army, severely weakening the empire during the Crisis of the Third Century. Its modern name commemorates St. Cyprian, bishop of Carthage, an early Christian writer who witnessed and described the plague, in his treatise On the Plague. The agent of the plague is highly speculative due to sparse sourcing, but suspects have included smallpox, measles, and viral hemorrhagic fever. The pandemic attacked everyone, "just and unjust", and the response to it has strong ties to Christian beliefs and religion.