Under the reign of Hārūn, Ibrāhīm b. al-Aghlab, the governor of Africa, succeeded in making himself independent of the central government, on condition of paying a fixed annual tribute to his suzerain the caliph. This was, if we do not take Spain into the account, the first instance of dismemberment, later to be followed by many others.
In the days of this caliph the first paper factories were founded in Bagdad.
6. Reign of Amīn.—On the death of Hārūn his minister, Fadl b. Rabī’, with the view of gaining the new caliph’s confidence, hastened to call together all the troops of the late caliph and to lead them back to Bagdad, in order to place them in the hands of the new sovereign, Amīn. He even, in direct violation of Hārūn’s will, led back the corps which was intended to occupy Khorasan under the authority of Mamun. Aware, however, that in thus acting he was making Mamun his irreconcilable enemy, he persuaded Amīn to exclude Mamun from the succession. Mamun, on receiving his brother’s invitation to go to Bagdad, was greatly perplexed; but his tutor and later vizier, Fadl b. Sahl, a Zoroastrian of great influence, who in 806 had adopted Islam, reanimated his courage, and pointed out to him that certain death awaited him at Bagdad. Mamun resolved to hold out, and found pretexts for remaining in Khorasan. Amīn, in anger, caused the will of his father, which, as we have seen, was preserved in the Ka‘ba, to be destroyed, declared on his own authority that Mamun’s rights of succession were forfeited, and caused the army to swear allegiance to his own son Mūsā, a child of five, on whom he bestowed the title of an-Nātiq bil-Haqq (“he who speaks according to truth”), a.h. 194 (a.d. 809-810). On hearing the news, Mamun, strong in the rightfulness of his claim, retaliated by suppressing the caliph’s name in all public acts. Amīn immediately despatched to Khorasan an army of 40,000 under the command of Ali b. ‘Īsā, who had regained his former influence, and told the caliph that, at his coming to Khorasan, all the leading men would come over to his side. Zobaida, the mother of the caliph, entreated Ali to treat Mamun kindly when he should have made him captive. It is said that Fadl b. Sahl had, through a secret agent, induced Fadl b. Rabī’ to select Ali, knowing that the dislike felt towards him by the Khorasanians would double their strength in fighting against him. Mamun, on his side, sent in all haste an army of less than 4000 men of his faithful Khorasanians, and entrusted their command to Ṭāhir b. Hosain, who displayed remarkable abilities in the war that ensued. The two armies met under the walls of Rai (Shaaban 195, May 811). By a bold attack, in the manner of the Kharijites of yore, Ṭāhir penetrated into the centre of the hostile army and killed Ali. The frightened army fled, leaving the camp with all its treasures to Ṭāhir, who from that day was named “the man with the two right hands.” A courier was despatched immediately to Merv, who performed the journey, a distance of about 750 miles, in three days. On the very day of his arrival, Harthama b. A‘yan had left Merv with reinforcements. Mamun now no longer hesitated to take the title of caliph.
When the news of Ali’s defeat came to Bagdad, Amīn sent Abdarrahmān b. Jabala to Hamadān with 20,000 men. Ṭāhir defeated him, forced Hamadān to surrender, and occupied all the strong places in Jabal (Media). The year after, Amīn placed in the field two new armies commanded respectively by Ahmad b. Mazyad and Abdallah b. Ḥomaid b. Qaḥṭaba. The skilful Ṭāhir succeeded in creating divisions among the troops of his adversaries, and obtained possession, without striking a blow, of the city of Holwān, an advantage which opened the way to the very gates of Bagdad. He was here reinforced by troops sent from Khorasan under the command of Harthama b. A‘yan, who was appointed leader of the war against Amīn, with orders to send Ṭāhir to Ahwāz. Ṭāhir continued his victorious march, conquered Ahwāz, took Wāsit and Madāin, and pitched his camp near one of the gates of the capital, where he was rejoined by Harthama. One after the other the provinces fell away from Amīn, and he soon found himself in possession of Bagdad alone. The city, though blockaded on every side, made a desperate defence for nearly two years. Ultimately the eastern part of the city fell into the hands of Ṭāhir, and Amīn, deserted by his followers, was compelled to surrender. He resolved to treat with Harthama, as he was averse to Ṭāhir; but this step caused his ruin. Ṭāhir succeeded in intercepting him on his way to Harthama, and immediately ordered him to be put to death. His head was sent to Mamun (September 813). It was presented to him by his vizier, Faḍl b. Sahl, surnamed Dhu‘l-Riyāsatain, or “the man with two governments,” because his master had committed to him both the ministry of war and the general administration. Mamun hid his joy beneath a feigned display of sorrow.
Amīn was only twenty-eight years old. As a ruler he was wholly incompetent. He hardly comprehended the importance of the affairs with which he was called upon to deal. He acted invariably on the advice of those who for the time had his confidence, and occupied himself mainly with the affairs of his harem, with polo, fishing, wine and music. The five years of his reign were disastrous to the empire, and in particular to Bagdad which never entirely recovered its old splendour.
7. Reign of Mamun.—On the day following the death of Amīn Ṭāhir caused Mamun to be proclaimed at Bagdad, and promised in his name a general amnesty. The accession of this prince appeared likely to restore to the empire the order necessary for its prosperity. It was not so, however. The reign of Mamun—that reign in which art, science and letters, under the patronage of the caliph, threw so brilliant a lustre—had a very stormy beginning. Mamun was in no haste to remove to Bagdad, but continued to reside at Merv. In his gratitude to Faḍl b. Sahl, to whose service he owed his success, he not only chose him as prime minister of the empire, but also named his brother, Hasan b. Sahl, governor of Media, Fārs, Ahwāz, Arabia and Irak. The two generals to whom he owed still more were not treated as they deserved. Harthama was ordered to return to Khorasan; Ṭāhir was made governor of Mesopotamia and Syria, with the task of subduing Naṣr b. Shabath, who with numerous adherents refused submission to the caliph. The Alids seized on the elevation of Mamun as a pretext for fresh revolts. At Kufa a certain Ibn Ṭabāṭabā placed an army in the field under Abu‘l-Sarāyā, who had been a captain in the army of Harthama. An army sent by Hasan b. Sahl was defeated, and Abu‘l-Sarāyā, no longer content to play a second part, poisoned his chief, Ibn Ṭabāṭabā, and put in his place another of the family of Ali, Mahommed b. Mahommed, whom, on account of his extreme youth, he hoped to govern at his will. Abu‘l-Sarāyā’s success continued, and several cities of Irak—Basra, Wāsit and Madāin—fell into his hands. Mecca, Medina and Yemen also were mastered by the Alids, who committed all kinds of atrocities and sacrilege. Abu‘l-Sarāyā, who even struck money in Kufa, began to menace the capital, when Hasan b. Sahl hastily sent a messenger to Harthama b. A‘yan, who was already at Holwān on his way back to Merv, entreating him to come to his aid. Harthama, who was deeply offended by his dismissal, refused at first, but at last consented, and at once checked the tide of disaster. The troops of the Alids were everywhere driven back, and the whole of Irak fell again into the hands of the Abbasids. Kufa opened its gates; Basra was taken by assault. Abu‘l-Sarāyā and Mahommed b. Mahommed fled to Mesopotamia, but were made prisoners. The former was decapitated, the latter was sent to Khorasan, the revolt in Arabia was quickly suppressed, and peace seemed within reach. This, however, was by no means the case. The disorder of civil war had caused a multitude of robbers and vagabonds to emerge from the purlieus of Bagdad. These ruffians proceeded to treat the capital as a conquered city, and it became necessary for all good citizens to organize themselves into a regular militia. Harthama, having vanquished Abu‘l-Sarāyā, did not go to Hasan b. Sahl, but proceeded towards Merv with the purpose of telling Mamun that the state of affairs was not as Fadl b. Sahl represented it to him, and urging him to come to Bagdad, where his presence was necessary. Fadl, informed of his intentions, filled the caliph’s mind with distrust against the old general, so that when Harthama arrived Mamun had him cast into prison, where he died shortly afterwards. When the tidings of his disgrace came to Bagdad, the people expelled the lieutenant of Hasan b. Sahl, called by them the Mājūzī (“the Zoroastrian”), who had chosen Madāin for his residence, and put at their head Mansūr, a son of Mahdi, who refused to assume the title of caliph, but consented to be Mamun’s vicegerent instead of Hasan b. Sahl.
Meanwhile, at Merv, Mamun was adopting a decision which fell like a thunderbolt on the Abbasids. In a.h. 201 (a.d. 817), under pretence of putting an end to the continual revolts of the partisans of Ali, and acting on the advice of his prime minister Fadl, he publicly designated as his successor in the Caliphate Ali ar-Ridā, a son of that Mūsā al-Kāzim who perished in the prison of Mahdi, a direct descendant of Hosain, the son of Ali, and proscribed black, the colour of the Abbasids, in favour of that of the house of Ali, green. This step was well calculated to delight the followers of Ali, but it could not fail to exasperate the Abbasids and their partisans. The people of Bagdad refused to take the oath to Ali b. Mūsā, declared Mamun deposed, and elected his uncle, Ibrāhīm, son of Mahdi, to the Caliphate.[33] It was only indirectly that the news reached the caliph, who then saw that Fadl had been treating him as a puppet. His anger was great, but he kept it carefully to himself. Fadl was one day found murdered, and Ali b. Mūsā died suddenly. The historians bring no open accusation against Mamun, but it seems clear that the opportune removal of these men was not due to chance. Mamun affected the profoundest grief, and, in order to disarm suspicion, appointed as his prime minister the brother of Fadl, Hasan b. Sahl, whose daughter Būrān he afterwards married. Soon after the news came to him that Hasan b. Sahl had become insane. Mamun appointed an officer to act as his lieutenant, and wrote that he was coming to Bagdad in a short time. From that moment the pseudo-caliph Ibrāhīm found himself deserted, and was obliged to seek safety in concealment. His precarious reign had, however, lasted nearly two years. Mamun had found out also that the general uneasiness was largely due to his treatment of Harthama and Tāhir, the latter having been put in a rebellious country without the men and the money to maintain his authority. The caliph therefore wrote to Tāhir to meet him at Nahrawān, where he was received with the greatest honour. Having taken all precautions, Mamun now made his solemn entry into Bagdad, but, to show that he came as a master, he still displayed for several days the green colours, though at last, at the request of Tāhir, he consented to resume the black. From this time, a.h. 204 (August 819), the real reign of Mamun began, freed as he now was from the tutelage of Faḍl.
When welcoming Tāhir, Mamun bade him ask for any reward he might desire. Tāhir, fearing lest the caliph, not being able to endure the sight of the murderer of his brother, should change his mind towards him, contrived to get himself appointed governor of Khorasan. Like most of the great Moslem generals, Tāhir, it is said, had conceived the project of creating an independent kingdom for himself. His death, a.h. 207 (a.d. 822), prevented its realization; but as his descendants succeeded him one after the other in the post of governor, he may be said in reality to have founded a dynasty in Khorasan. His son Abdallah b. Tāhir was a special favourite of Mamun, He brought Naṣr b. Shabath to subjection in Mesopotamia, and overcame by great ability a very dangerous rebellion in Egypt. When he returned thence, the caliph gave him the choice between the government of Khorasan and that of the northern provinces, where he would have to combat Babak the Khorramite. Abdallah chose the former (see below, § 8).
The pseudo-caliph, Ibrāhim, who, since Mamun’s entry into Bagdad, had led a wandering life, was eventually arrested. But Mamun generously pardoned him, as well as Faḍl b. Rabi’, the chief promoter of the terrible civil war which had so lately shaken the empire. After that time, Ibrahim lived peacefully at the court, cultivating the arts of singing and music.
Tranquillity being now everywhere re-established, Mamun gave himself up to science and literature. He caused works on mathematics, astronomy, medicine and philosophy to be translated from the Greek, and founded in Bagdad a kind of academy, called the “House of Science,” with a library and an observatory. It was also by his orders that two learned mathematicians undertook the measurement of a degree of the earth’s circumference. Mamun interested himself too in questions of religious dogma. He had embraced the Motazilite doctrine about free will and predestination, and was in particular shocked at the opinion which had spread among the Moslem doctors that the Koran was the uncreated word of God. In the year 212 (a.d. 827) he published an edict by which the Motazilite (Mu’tazilite) doctrine was declared to be the religion of the state, the orthodox faith condemned as heretical. At the same time he ordered all his subjects to honour Ali as the best creature of God after the Prophet, and forbade the praise of Moawiya. In a.h. 218 (a.d. 833) a new edict appeared by which all judges and doctors were summoned to renounce the error of the uncreated word of God. Several distinguished doctors, and, among others, the celebrated Ahmad b. Ḥanbal (q.v.), founder of one of the four orthodox Moslem schools, were obliged to appear before an inquisitorial tribunal; and as they persisted in their belief respecting the Koran, they were thrown into prison. Mamun, being at Tarsus, received from the governor of Bagdad the report of the tribunal, and ordered that the culprits should be sent off to him. Happily for these unfortunate doctors, they had scarcely reached Adana, when news of the caliph’s death arrived and they were brought back to Bagdad. The two successors of Mamun maintained the edicts—Ahmad b. Ḥanbal, who obstinately refused to yield, was flogged in the year 834— but it seems that Motasim did not himself take much interest in the question, which perhaps he hardly understood, and that the prosecution of the inquisition by him was due in great part to the charge which was left him in Mamun’s will. In the reign of Motawakkil the orthodox faith was restored, never to be assailed again.[34]