Original:  In spring 216 he arrived again at Antioch and before 27 May had set out for his Persian War. For the winter of 215/216 he was at Edessa.
Revised:  In spring 216 he arrived again at Antioch and before 27 May had set out to lead his Roman army against the Parthians. During the winter of 215/216 he was at Edessa.
Edit intent: others