Along with his brothers, Abd al-Malik and Isa, Ishaq was one of the commanders of Marwan ibn Muhammad (the future Marwan II) during the latter's governorship in Armenia and Adharbayjan and his campaigns against the Khazars. Thus in 738 he defeated the Caucasian prince Tuman Shah and captured his strongholds. In 743/744, he was appointed as commander of Derbent (Bab al-Abwab) and governor of the combined province of Armenia and Adharbayjan, and he accompanied Marwan in 745/746 in the fighting in the Jazira, during the Third Fitna. He then returned to his governorship in Armenia, which he seems to have kept until the end of the Umayyad Caliphate in 749/750.