Parthian Empire
The legions I, II, and III "Parthica" were levied by Septimius Severus for his campaign against the Parthian Empire. After the success of this campaign, I and III "Parthica" remained in the region, in the camp of Singara (Sinjar, Iraq), in Mesopotamia, to prevent subsequent rebellions and to guard the eastern provinces from attacks from the Parthian Empire.