Caracalla 's successor , the Praetorian Prefect of the Guard Macrinus , was defeated at Nisibis and concluded a peace with Artabanus , in which he gave up all the Roman conquests , restored the booty , and paid a heavy contribution to the Parthians .
Caracalla 's successor , the Praetorian Prefect of the Guard Macrinus , was defeated at Nisibis and in a peace with Artabanus he gave up all the Roman conquests and paid a heavy contribution to the Parthians .