Hisham ibn Abd al-Malik
Constantine was crossing Asia Minor to campaign against the Umayyad Caliphate under Hisham ibn Abd al-Malik on the eastern frontier in June 741 or 742. But during this course Constantine was attacked by the forces of his brother-in-law Artabasdos, the stratēgos of the Armeniac theme. Artabasdos was the husband of Anna, an older sister of Constantine.