Harthama ibn A ' yan Harthama ibn A ' yan ( died June 816 ) was a Khurasan - born general and governor of the early Abbasid Caliphate , serving under the caliphs al - Hadi , Harun al - Rashid and al - Ma ' mun . He played an important role in the victory of al - Ma ' mun in the Abbasid civil war , but was executed at his orders when he protested against the power of the Sahlid family that dominated his court . Biography . He first appears during the reign of the second Abbasid Caliph , al - Mansur ( reign ed 754 – 775 ) , as one of the supporters of the Abbasid prince and heir - apparent Isa ibn Musa . Isa was forced to renounce his claim on the throne in favour of al - Mansur ' s son , al - Mahdi ( r . 775 – 785 ) , who had Harthama brought to Baghdad in chains and kept him under arrest throughout his reign . Under al - Mahdi ' s son and successor al - Hadi ( r . 785 – 786 ) , however , he was released and rose to prominence as one of the Caliph ' s closest advisors . At one point he is said to have recommended that the Caliph should execute his younger brother and heir - apparent , the future caliph Harun al - Rashid ( r . 786 – 809 ) to open the path for the succession of al - Hadi ' s own sons , but this plan was foiled through the intervention of the Caliph ' s mother , al - Khayzuran . Nevertheless , when al - Hadi died it was Harthama himself who released Harun from prison . He continued to enjoy a privileged position and high office under Harun as well , serving as governor of Palestine , Egypt , Mosul and then Ifriqiya , before assuming command of the caliphal guard ( " haras " ) under the supervision of Harun ' s truseted vizier , Ja ' far ibn Yahya the Barmakid . From this post he played a role in the downfall of the Barmakids in 803 , and established himself as one of the Caliphate ' s senior military leaders . He also led two summer raids into Asia Minor against the Byzantines . When the large - scale rebellion of Rafi ibn al - Layth broke out in Khurasan in 805 – 806 and the local governor , Ali ibn Isa ibn Mahan , proved himself incapable of suppressing it , al - Rashid sent Harthama to replace him , following himself shortly after , in 808 . Harthama was in Samarkand when al - Rashid died at Tus in March 809 , and remained in the east after . Consequently he threw in his lot with al - Ma ' mun ( r . 813 – 832 ) in the civil war against al - Amin ( r . 811 – 813 ) , and was along with Tahir ibn Husayn one of the two commanders of al - Ma ' mun ' s army during the crucial year - long siege of Baghdad in 812 – 813 . During the siege he led the attack from the east while Tahir commanded from the west . In the final stage of the siege , Harthama tried unsuccessfully to secure the surrender and life of al - Amin , by sending a boat to ferry him over the Tigris . The boat , however , capsized , and al - Amin was captured and executed by Tahir ' s men . Harthama remained in Iraq after that , and played a leading role in defeating the pro - Alid revolt of Abu ' l - Saraya al - Sirri in 815 . Soon after he was appointed as governor of Arabia and Syria , but instead of taking up his post Harthama went east with the intention of appraising al - Ma ' mun , who had remained in Merv , of the real situation in Iraq , ans especially the resentment caused by the government ' s domination by a group of Khurasanis around al - Ma ' mun ' s vizier , al - Fadl ibn Sahl . Al - Fadl and his supporters were however able to turn al - Ma ' mun against Harthama , who was imprisoned and executed in June 816 . In response to the news of his execution , Harthama ' s son Hatim , the governor of Arminiya , led a rebellion that was however cut short by his own death . Another son , A ' yan , governor of Sistan ca . 820 , is also known , and his descendants through Hatim continued to occupy high offices until well into the 9th century .