In the summer of 161, the Parthian Vologases IV invaded Armenia, expelled the ruler Sohaemus placed there by the Romans, and installed his own relative Pacoras as king. Being governor of Cappadocia meant Severianus would be on the front line of any conflict involving Armenia, Alexander of Abonutichus had enraptured Severianus, as he had the proconsul Rutilianus. Alexander convinced Severianus that he could defeat the Parthians easily, and win glory for himself. Severianus led a legion (perhaps the IX "Hispana") into Armenia, but was trapped by the Parthian general Chosrhoes at Elegeia, a town just beyond the Cappadocian frontiers, near the headwaters of the Euphrates. Severianus made some attempt to fight Chosrhoes, but soon realized the futility of his campaign, and committed suicide. His legion was massacred. The campaign had only lasted three days. He was replaced as governor of Cappadocia by Marcus Statius Priscus.