al-Abbas ibn al-Ma'mun
Al-Abbas ibn al-Ma'mun (died 838 CE) was an Arab prince and general, the son of the Abbasid Caliph al-Ma'mun (r. 813–833 CE). A distinguished military leader in the Byzantine–Arab Wars, he was passed over in the succession in favour of his uncle al-Mu'tasim (r. 833–842 CE). In 838, he was arrested for his involvement in a failed conspiracy against Mu'tasim, and died in prison.
Abbas was the only son of Ma'mun, who in 828–829 appointed him as governor of Al-Jazira (Upper Mesopotamia) and the Mesopotamian military frontier zone (thughur) with the Byzantine Empire. Abbas distinguished himself in the expeditions against Byzantium for his bravery. In the summer of 830, Abbas led an expedition against the Khurramite rebels of Babak Khorramdin in Azerbaijan. The campaign was accompanied by a contingent of Byzantine captives under the renegade general Manuel the Armenian, who, given Abbas's relative inexperience, may have been the actual commander of the army. Abbas's force met with some success against the Khurramites, and began its return. As it passed near the Byzantine frontier at Adata, Manuel, having earned the confidence of Abbas and his Arab officers, persuaded Abbas to cross the nearby passes and raid Byzantine territory. Once there, Manuel took advantage of a hunt to disarm Abbas and his entourage and defect back to the Empire, along with some of the other Byzantine captives. Abbas with his men were left behind and after rejoining their army, they retreated back over the mountains into the Caliphate.
In the next year, however, Abbas accompanied his father and uncle in a major expedition into Byzantine Anatolia. After the Arab army crossed the Cilician Gates and took Heraclea Cybistra in early July, it divided in three corps, headed by the Caliph, Mu'tasim and Abbas, and proceeded to raid across Cappadocia. The other two forces achieved little of consequence in the already repeatedly devastated area, but Abbas met with more success: he forced the town of Tyana to capitulate and razed it, and met and defeated the Byzantine army under the emperor Theophilos (r. 829–842) in a minor skirmish. Ma'mun kept up the pressure on Byzantium in 832, with his army capturing the strategically important fortress of Loulon, and in late 832 the Caliph began gathering a huge army and announced that he intended to conquer and colonize Anatolia step by step, and finally subjugate the Empire by capturing Constantinople itself. Consequently, on 25 May 833, Abbas with the advance force marched into Byzantine territory and began creating a military base at the site of Tyana. The site had been fortified and awaited the arrival of the Caliph's army, which in early July crossed into Anatolia. At this juncture, fortunately for the Byzantines, Ma'mun fell ill and died, although some modern scholars speculate that his death may have been the result of a coup.
Although Abbas was Ma'mun's son, the Caliph apparently had named his brother Mu'tasim as his heir shortly before his death. Abbas swiftly swore allegiance to Mu'tasim, but this turn of events was not popular among the assembled army, which tried to proclaim Abbas caliph. Abbas refused, and managed to assuage the troops' anger. Nevertheless, Mu'tasim's hold on the throne was still shaky, and he abandoned Ma'mun's campaign; the new base at Tyana was razed, and the army returned to the Caliphate. Despite his acceptance of his uncle's succession, Abbas became the focus of the factions opposed to Mu'tasim, and in particular his increasing reliance on and favour shown to his Turkish slave-soldiers (ghilman). This discontent resulted in a conspiracy led by the general 'Ujayf ibn 'Anbasa which aimed to kill Mu'tasim and place Abbas, who was aware of the plot, on the throne. The conspiracy was uncovered while Mu'tasim was campaigning against the Byzantines, with the Caliph informed of it just after his army had sacked Amorium. The resulting investigation, headed by Mu'tasim's trusted Turkish general Ashinas, resulted in the execution of most conspirators. This was broadened into a virtual purge of the army, in which the hitherto dominant Khurasani element was replaced with Mu'tasim's favoured Turks. Abbas himself was imprisoned and died in prison at Manbij in 838, while his male descendants were imprisoned and executed by Ashinas.
- Gordon, Matthew (2001). The Breaking of a Thousand Swords: A History of the Turkish Military of Samarra, A.H. 200–275/815–889 C.E. Albany, New York: State University of New York Press. ISBN 978-0-7914-4795-6.
- Treadgold, Warren T. (1988). The Byzantine Revival, 780–842. Stanford, California: Stanford University Press. ISBN 0-8047-1462-2.
- Zetterstéen, K. V. (1986). "al-'Abbās b. al-Ma'mūn". In Gibb, Hamilton Alexander Rosskeen. The Encyclopedia of Islam, New Edition, Volume I: A–B. Leiden and New York: Brill. pp. 11–12. ISBN 90-04-08114-3.