When Umar's general, 'Amr ibn al-'As known to the Romans as Amru, threatened the Prefecture of Egypt, Cyrus was made prefect and entrusted with the conduct of the war. Certain humiliating stipulations, to which he subscribed for the sake of peace, angered his imperial master so much that he was recalled and harshly accused of connivance with the Rashidun Caliphate; however, he was soon restored to his former authority, owing to the impending siege of Alexandria, but could not avert the fall of the great city in 640. He signed a peace treaty that surrendered Alexandria and Egypt on 8 November 641 before dying in 642.[5]