Isa ibn Musa

ʿĪsā ibn Mūsā ibn Muḥammad ibn ʿAlī ibn ʿAbd Allāh ibn ʿal-ʿAbbās (Arabic: عيسى بن موسى بن محمد بن علي بن عبد الله بن العباس; c. 721–783/4) was a nephew of the first two Abbasid caliphs, al-Saffah (r. 750–754) and al-Mansur (r. 754–775). He served as governor of Kufa in Iraq for fifteen years and led the suppression of the Alid revolt of 762–763. From 754 on he was also heir-apparent of the Caliphate, until he was pressured to cede precedence to al-Mansur's son al-Mahdi (r. 775–785) in 764. With al-Mahdi's accession in 775, he was forced to renounce his rights entirely in 776 in favour of al-Hadi (r. 785–786), and retire to his palace at al-Ukhaidir Fortress, where he died in 784.

Isa ibn Musa was born in AH 103 (721/2 CE).^[1] In summer 750, immediately after the end of the Abbasid Revolution, Isa was appointed by his uncle and first Abbasid caliph, al-Saffah, as governor of Kufa, the first seat of the Abbasid government. He would retain the post for fifteen years—according to Hugh N. Kennedy, the second longest tenure in the Abbasid period after that of Dawud ibn Yazid al-Muhallabi at Sind in the early 9th century.^[2][3]

In 754, as al-Saffah was nearing his death, and as his designated heir Abu Ja'far (who reigned as caliph al-Mansur) was on the Hajj pilgrimage in Mecca at the time, the Caliph appointed Isa, then about 34 years old, as the second heir, in the event anything should happen to Abu Ja'far. This move was necessary to prevent Abu Muslim, the powerful and popular commander who had initiated the Abbasid Revolution in Khurasan and had ruled the province since, from rising to the position of king-maker. Isa had already proven his ability as governor, and his proximity to the capital, al-Anbar, was crucial for a swift succession.^[2][4] When al-Saffah finally died, Isa proclaimed Abu Ja'far as Caliph and sent riders to notify him of his accession. According to the sources recorded by al-Tabari, Isa placed guards before the treasuries and government offices in the capital, until the new caliph arrived there. He also sent al-Saffah's chamberlain, Abu Ghassan, to inform Abdallah ibn Ali in Syria of al-Saffah's death and receive the oath of allegiance (bay'ah) from him.^[5]

In the event, when al-Saffah died on 8 June 754, Abu Muslim, who was on the pilgrimage together with al-Mansur, did not oppose the latter's accession, and readily swore the oath to him.^[6] It was Abdallah ibn Ali in Syria who rose in revolt instead, commandeering an army he had originally raised to campaign against the Byzantine Empire and marching with it into Iraq.^[7] The revolt was defeated by Abu Muslim,^[8] whereupon Isa intervened to grant Abd al-Samad ibn Ali, who alone among Abdallah's brothers had supported his revolt, a pardon.^[9] Isa had cordial relations with Abu Muslim, and was left unaware of al-Mansur's plot to kill the dangerously powerful ruler of Khurasan until after the deed was done.^[10] Under al-Mansur, Isa remained as governor of Kufa, and took actively part in the planning of the new Abbasid capital, Baghdad.^[2]

In 762–763, Isa led the army and suppressed the Alid revolts under the brothers Muhammad al-Nafs al-Zakiyya and Ibrahim ibn Abdallah.^[2] Muhammad's choice of Medina to raise his revolt was a potent symbol but a strategic error, as al-Mansur immediately realised. The Caliph sent Isa with 4,000 men against Muhammad. The Abbasid army easily cut the city off from outside support and quickly overran Muhammad's supporters, who numbered only about 300 men. Muhammad himself was killed, and Isa sent his head to Caliph al-Mansur.^[11][12] Muhammad's brother Ibrahim, who had chosen Basra as his base, was more successful, capturing Wasit, Fars, and Ahwaz, but failed to synchronise his revolt with the uprising of Medina. As a result, Isa was able to suppress Muhammad in Medina and then bring his forces against the Basra rebels. With some 15,000 men, Isa met some 10,000 rebels on 14 February 763 at Bakhamra. There the Alids initially gained the upper hand, but in the end Isa's perseverance brought the Abbasids victory.^[13][14]

As soon as al-Mansur's position on the throne was secure, he began preparations for sidelining Isa from the succession in favour of his own son, Muhammad, the future al-Mahdi (r. 775–785).^[15] He was named heir after Isa in 758/9,^[16] and then appointed governor of Khurasan and the entire eastern caliphate in 759/60.^[17] This enabled him to establish close contacts with the vital Khurasani army, which had spearheaded the Abbasid Revolution. In time, Muhammad gained the fervent support of the Khurasanis, who in turn strongly opposed the succession of Isa. The reasons for this are not entirely clear, but Kennedy suggests that Isa may have been associated with the aristocratic gentry, the dehqan class, the overthrow of whose power had been one of the aims of the Abbasid Revolution.^[18]

Despite Isa's leading role in suppressing the Alid revolts, almost immediately the Caliph began applying pressure to accept the precedence of Muhammad as heir, while Isa would be relegated to heir of the much younger Muhammad, in effect disinherited.^[19] After Isa refused to comply, al-Mansur resorted to trickery: he entrusted Isa with watching over the defeated rebel Abdallah ibn Ali, and then secretly ordered Isa to execute him, aiming to pin responsibility for this on Isa and make him the object of the revenge of Abdallah's numerous and influential brothers. Isa was saved through the perspicacity of his secretary, who understood the caliphal trap, and prevented the secret order from being carried out. Thus, when called upon to present Abdallah to his brothers, Isa was able to expose the caliph's machinations.^[19]

In response, in 764 al-Mansur removed Isa from the governorship of Kufa,^[20] but his family remained influential in the city for decades to come: his son Musa held the governorship of Basra four times later in the century.^[21] Not only was Isa not given another office, but al-Mansur began to publicly berate and humiliate him, hoping to provoke a reaction. Isa retained his composure throughout, not rising to the caliph's bait.^[22] In the end, it was the intervention of the Khurasani soldiery, who made clear that they would not countenance Isa's succession, that forced him to back down; through the intercession of either Salm ibn Qutayba or Khalid ibn Barmak, Isa agreed to relinquish his place in the succession to Muhammad in exchange for an enormous sum of money.^[18] Isa nevertheless remained a threat to al-Mansur's rule: his dismissal is given as one of the reasons of the revolt of Ustadh Sis in Khurasan in 768,^[23] and as late as 770 some Khurasanis were arrested and brought to Baghdad for championing his cause.^[15] On his deathbed, al-Mansur is said to have remarked that he feared only two men, Isa ibn Musa and Isa, the son of Zayd ibn Ali.^[24]

In retirement, Isa built the al-Ukhaidir Fortress, a sprawling fortified palace that, in the words of Kennedy, "demonstrates to this day the power and wealth of the family".^[2][3] He spent most of his final years there as a semi-recluse, only leaving it to visit Kufa for the Eid al-Fitr and Eid al-Adha.^[25]

In 775, al-Mansur summoned Isa to take part, along with other members of the dynasty, in the Hajj, during which the caliph died.^[24] Upon al-Mansur's death his chamberlain, Rabi ibn Yunus, extracted the oath of allegiance from Isa and the caliph's entourage, before making al-Mansur's death public.^[26] While al-Mahdi's accession was unopposed, Isa was again the heir apparent, a situation that the Khurasani troops vehemently and vocally opposed.^[27] Al-Mahdi summoned him to Baghdad, but Isa refused, until soldiers took him prisoner at Kufa during Eid al-Adha in October 776. In the capital, he was faced with riots and demonstrations by the troops, who demanded that he abdicate his position entirely. In November he was obliged to witness the proclamation and oath-taking for al-Mahdi's son, Musa (the future al-Hadi, r. 785–786), as heir, and renounce his rights in public and in writing.^[25] He was compensated by another vast sum of money, some ten million silver dirhams, as well as estates in Upper Mesopotamia, but he was, as Kennedy writes, "a broken man". He retired from public life entirely until his death in June/July 784.^[25]

• Kennedy, Hugh (1981). The Early Abbasid Caliphate: A Political History. London: Croom Helm. ISBN 0389200182.
• McAuliffe, Jane Dammen, ed. (1995). The History of al-Ṭabarī, Volume XXVIII: The ʿAbbāsid Authority Affirmed: The Early Years of al-Mansūr, A.D. 753–763/A.H. 136–145. SUNY Series in Near Eastern Studies. Albany, New York: State University of New York Press. ISBN 978-0-7914-1895-6.
• Sourdel, D. (1978). "ʿĪsā b. Mūsā". In van Donzel, E.; Lewis, B.; Pellat, Ch. & Bosworth, C. E. (eds.). The Encyclopaedia of Islam, Second Edition. Volume IV: Iran–Kha. Leiden: E. J. Brill. p. 88. OCLC 758278456.