Al-Ma'mun
Abū al-ʿAbbās Abd Allāh ibn Hārūn al-Maʾmūn, better known by his regnal name al-Ma'mun, was the seventh Abbasid caliph, who reigned from 813 until his death in 833. His leadership was marked by the power and prosperity of the Abbasid Caliphate. Al-Ma'mun promoted the Graeco-Arabic translation movement, the flowering of learning and the sciences in Baghdad, and the publishing of al-Khwarizmi's book now known as "Algebra", making him one of the most important caliphs in the Islamic Golden Age. He is also known as a proponent of the rational Islamic theology of Mu'tazilism.
Al-Ma'mun succeeded his half-brother al-Amin after a civil war, much of his reign was spent on peace campaigns. His strong support for Mu'tazilism and the people of Kalam led him to persecute the supporters of Hadith and imprison a Sunni Imam, Ahmad ibn Hanbal in an event that became known as the Mihna. Al-Ma'mun's foreign policy was due to his decision to continue war and diplomatic relations with the Byzantine Empire, the tension between conflict or diplomacy varying during his military campaigns.
Birth and education
Abdallah, the future al-Ma'mun, was born in Baghdad on the night of 13 to 14 September 786 CE to Harun al-Rashid and his concubine Marajil, from Badghis. On the same night, which later became known as the "night of the three caliphs", his uncle al-Hadi died and was succeeded by Ma'mun's father, Harun al-Rashid, as ruler of the Abbasid Caliphate. Marajil died soon after his birth, and Abdallah was raised by Harun al-Rashid's wife, Zubayda, herself of high Abbasid lineage as the granddaughter of Caliph al-Mansur. As a young prince, Abdallah received a thorough education: al-Kisa'i tutored him in classical Arabic, Abu Muhammad al-Yazidi in adab, and he received instruction in music and poetry. He was trained in fiqh by al-Hasan al-Lu'lu'i, showing particular excellence in the Hanafi school, and in the hadith, becoming himself active as a transmitter. According to M. Rekaya, "he was distinguished by his love of knowledge, making him the most intellectual caliph of the Abbasid family, which accounts for the way in which his caliphate developed".Appointment as successor and Governor of Khurasan
Although Abdallah was the oldest of his sons, in 794 Harun named the second-born Muhammad, born in April 787 to Zubayda, as the first in line of succession. This was the result of family pressure on the Caliph, reflecting Muhammad's higher birth, as both parents descended from the Abbasid dynasty; indeed, he remained the only Abbasid caliph to claim such descent. Muhammad received the oath of allegiance with the name of al-Amin, first in Khurasan by his guardian, the Barmakid al-Fadl ibn Yahya, and then in Baghdad. Abdallah was recognized as second heir only after entering puberty, in 799, under the name al-Ma'mun, with another Barmakid, Ja'far ibn Yahya, as his guardian. At the same time, a third heir, al-Qasim, named al-Mu'tamin, was appointed, under the guardianship of Abd al-Malik ibn Salih.These arrangements were confirmed and publicly proclaimed in 802, when Harun and the most powerful officials of the Abbasid government made the pilgrimage to Mecca. Al-Amin would succeed Harun in Baghdad, but al-Ma'mun would remain al-Amin's heir and would additionally rule over an enlarged Khurasan. This was an appointment of particular significance, as Khurasan had been the starting point of the Abbasid Revolution which brought the Abbasids to power, and retained a privileged position among the Caliphate's provinces. Furthermore, the Abbasid dynasty relied heavily on Khurasanis as military leaders and administrators. Many of the original Khurasani Arab army that came west with the Abbasids were given estates in Iraq and the new Abbasid capital, Baghdad, and became an elite group known as the abnāʾ al-dawla. This large-scale presence of an Iranian element in the highest circles of the Abbasid state, with the Barmakid family as its most notable representatives, was certainly a factor in the appointment of al-Ma'mun, linked through his mother with the eastern Iranian provinces, as heir and governor of Khurasan. The stipulations of the agreement, which were recorded in detail by the historian al-Tabari, accorded al-Mamun's Khurasani viceroyalty extensive autonomy. However, modern historians consider that these accounts may have been distorted by later apologists of al-Ma'mun in the latter's favour. Harun's third heir, al-Mu'tamin, received responsibility over the frontier areas with the Byzantine Empire in Upper Mesopotamia and Syria.
Very quickly, the latent rivalry between the two brothers had important repercussions: almost immediately after the court returned to Baghdad in January 803, the Abbasid elites were shaken by the abrupt fall of the Barmakid family from power. On the one hand, this event may reflect the fact that the Barmakids had become indeed too powerful for the Caliph's liking, but its timing suggests that it was tied to the succession issue as well: with al-Amin siding with the abnāʾ and al-Ma'mun with the Barmakids, and the two camps becoming more estranged every day, if al-Amin was to have a chance to succeed, the power of the Barmakids had to be broken.
Al-Fadl ibn Sahl, a Kufan of Iranian origin whose father had converted to Islam and entered Barmakid service, replaced Ja'far ibn Yahya as al-Ma'mun's tutor. In 806 he also became al-Ma'mun's secretary, an appointment that marked him out as the chief candidate for the vizierate should al-Ma'mun succeed to the throne. In 804, al-Ma'mun married his cousin, Umm Isa, a daughter of the Caliph al-Hadi. The couple had two sons, Muhammad al-Asghar and Abdallah.
The years after the fall of the Barmakids saw an increasing centralization of the administration and the concomitant rise of the influence of the abnāʾ, many of whom were now dispatched to take up positions as provincial governors and bring these provinces under closer control from Baghdad. This led to unrest in the provinces, especially Khurasan, where local elites had a long-standing rivalry with the aabnāʾ and their tendency to control the province from Iraq. The harsh taxation imposed by a prominent member of the abnāʾ, Ali ibn Isa ibn Mahan, even led to a revolt under Rafi ibn al-Layth, which eventually forced Harun himself, accompanied by al-Ma'mun and the powerful chamberlain and chief minister al-Fadl ibn al-Rabi, to travel to the province in 808. Al-Ma'mun was sent ahead with part of the army to Merv, while Harun stayed at Tus, where he died on 24 March 809.
Abbasid civil war
In 802 Harun al-Rashid, father of al-Maʾmūn and al-Amin, ordered that al-Amin succeed him, and al-Ma'mun serve as governor of Khurasan and as caliph after the death of al-Amin. In the last days of Harun's life his health was declining and saw in a dream Musa ibn Jafar sitting in a chamber praying and crying, which made Harun remember how hard he had struggled to establish his own caliphate. He knew the personalities of both his sons and decided that for the good of the Abbasid dynasty, al-Maʾmūn should be caliph after his death, which he confided to a group of his courtiers. One of the courtiers, Fadl ibn Rabi', did not abide by Harun's last wishes and convinced many in the lands of Islam that Harun's wishes had not changed. Later the other three courtiers of Harun who had sworn loyalty to Harun by supporting al-Maʾmūn, namely, 'Isa Jarudi, Abu Yunus, and Ibn Abi 'Umran, found loopholes in Fadl's arguments, and Fazl admitted Harun had appointed al-Maʾmūn after him, but, he argued, since Harun was not in his right mind, his decision should not be acted upon. Al-Maʾmūn was reportedly the older of the two brothers, but his mother was a Persian woman while al-Amin's mother was a member of the reigning Abbasid family. After al-Rashid's death in 809, the relationship between the two brothers deteriorated. In response to al-Ma'mun's moves toward independence, al-Amin declared his own son Musa to be his heir. This violation of al-Rashid's testament led to a succession struggle. Al-Amin assembled a massive army at Baghdad with 'Isa ibn Mahan at its head in 811 and invaded Khorasan, but al-Maʾmūn's general Tahir ibn al-Husayn destroyed the army and invaded Iraq, laying siege to Baghdad in 812. In 813 Baghdad fell, al-Amin was beheaded, and al-Maʾmūn became the undisputed Caliph.Internal strife
Sahl ibn Salama al-Ansari
There were disturbances in Iraq during the first several years of al-Maʾmūn's reign, while the caliph was in Merv. On 13 November 815, Muhammad ibn Ja'far al-Sadiq claimed the Caliphate for himself in Mecca. He was defeated and he quickly abdicated asserting that he had only become caliph on news that al-Ma'mun had died. Lawlessness in Baghdad led to the formation of neighborhood watches with religious inspiration, with two notable leaders being Khalid al-Daryush and Sahl ibn Salama al-Ansari. Sahl adopted the slogan, la ta'a lil- makhluq fi ma'siyat al-khaliq, or 'no obedience to the creature in disobedience of the Creator', alluding to what he saw as "the conflict... between God's will and Caliphal authority". "Most" of the leadership of this vigilante movement came from the sulaahd and from "popular preachers" ; its followers were called the 'amma,. The volunteers of the movement were known as mutawwi'a, which was the same name given to "volunteers for frontier duty and for the holy war against Byzantium".Sahl's and movement influence was such that military chiefs first "delayed capitulation to al-Ma'mun" and adopted Sahl's religious "formula" until they became alarmed at his power and combined to crush him in 817–18 CE.
Imam al-Rida
In A.H. 201 al-Ma'mun named Ali ar-Rida as his heir as caliph. This move may have been made to appease Shi'ite opinion in Iraq and "reconcile the 'Alid and 'Abbasid branches of the Hashimite family", but in Baghdad it caused the Hashimites—supported by "military chiefs of al-Harbiyya, including Muttalib and 'Isa ibn Muhammad"—to depose al-Ma'mun and elect Ibrahim ibn al-Mahdi Caliph.According to Shia sources, the deposing of al-Ma'um in Baghdad was not out of opposition to the wise and pious Imam Reza, but because of rumors spread by Fazl ibn Sahl. Al-Ma'mun moved Imam Reza to Merv in hopes of keeping watch over him, but was foiled by the Imam's growing popularity there. People from all over the Muslim world traveled to meet the prophet's grandson and listen to his teachings and guidance. In an attempt to humiliate the Imam, al-Ma'mun set him up with the greatest scholars of the world's religions, but the Imam prevailed and then informed al-Ma'mun that his grand vizier, Fazl ibn Sahl, had withheld important information from him.
In Baghdad, al-Maʾmūn was unseated and replaced by Ibrahim ibn Mehdi not because al-Maʾmūn's naming Imam Reza as his heir was unpopular, but because of "rumors" spread by Fazl ibn Sahl.
Seeking to put down the rebellion in Baghdad, al-Ma'mun set out for the city on 12 April 818. At Tus, he stopped to visit his father's grave. However, when they reached the town of Sarakhs, his vizier, Fazl ibn Sahl, was assassinated, and when they reached Tus, the Imam was poisoned. Al-Ma'mūn ordered that the Imam be buried next to the tomb of his own father, Harun al-Rashid, and showed extreme sorrow in the funeral ritual and stayed for three days at the place. Nonetheless, Shia tradition states he was killed on orders of al-Ma'mun, and according to Wilferd Madelung the unexpected death of both the vizier and the successor, "whose presence would have made any reconciliation with the powerful ʿAbbasid opposition in Baghdad virtually impossible, must indeed arouse strong suspicion that Ma'mun had had a hand in the deaths."
Following the death of Imam Reza, a revolt took place in Khurasan. Al-Ma’mun tried unsuccessfully to absolve himself of the crime.