The plague under Commodus as an unintended consequence of Roman grain market regulation.

This paper begins with a review of Roman grain market policies. It is argued that policies such as forced sales and maximum prices made urban consumers hesitant to rely on the market for secure access to grain. Consequently, consumers hoarded grain in their homes. The hoarded grain formed a volatile fuel ready to be ignited by the arrival of the bubonic plague bacillus. This scenario fits events in the city of Rome under Commodus. Attested grain market interventions were followed by a severe epidemic, arguably bubonic plague, which decimated the city's population.