Al-Ma’mun and al-Mu‘tasim

Muslim–Byzantine warfare abated after the death of Harun al-Rashid in 809. Prolonged internal troubles within the caliphate limited the ability of Harun’s successors to take the offensive against Byzantium. This period also saw bands of autonomous, armedMuslims marauding into Anatolia. In Byzantium, too, internal conflicts – notably the revolt of Thomas the Slav (see above, pp. 258–9) – severely limited the ability of Emperor Michael II (820–29) to wage war on theMuslims in the east in the early 820s. Thomas’ revolt received additional impetus and reinforcements from diehard followers of the defeated al-’Amin, brother of Caliph al-Ma’mun (813–33). Among these were Zawaqil bedouin from Syria, who had no other refuge as they fled from the manhunts and reprisals carried out by the caliph’s soldiers. But they were unable to give Thomas’ insurgency enough additional resources to bring him victory. Internal violence in the caliphate brought further reinforcements into the Byzantine empire, of rather mixed value. After the crushing in 838 of Babek’s Khurramite rebellion, which may have received Byzantine support, the remaining rebels fled into Byzantine territory where they were incorporated into the armies of Emperor Theophilos (829–42) and placed under the command of the controversial Theophobos. These separate armed bands of Khurramites brought to Byzantium not only experienced manpower but also valuable information about Muslim military matters. Their relative prominence in the course of events testifies to the shortage of adequate Byzantine soldiers to fight the Muslims. However, these recruits, who are termed ‘Persians’ in the Byzantine sources, did not necessarily make for stability. They were liable to switch sides and so could, in their turn, provide important intelligence back to the Muslims.65 Caliph al-Ma’mun assigned northern Mesopotamia, and the border fortress districts of the thughur and the ‘awasim to his son al-‘Abbas, together with the sum of 500,000 dinars. The civil war between al-Ma’mun and his brother al-’Amin had significantly weakened the Abbasids’ position vis- `a-vis Byzantium. Nevertheless, al-Ma’mun was determined to redress the balance and in 830 he launched a series of offensives, invading Cappadocia in response to Emperor Theophilos’ attack on Mopsuestia and Tarsus. He captured and fortified the city of Tyana, and even claimed that he would conquer Constantinople itself. A second campaign into Asia Minor was mounted the following year. In 832, al-Ma’mun forced the major border fortress of Lulon to surrender, and in 833 he tried, albeit unsuccessfully, to capture Amorion. He died while planning further offensives against the Byzantine frontier regions: having recaptured Tyana, al-Ma’mun was preparing an expedition to implant Arab tribesmen in Anatolia. Al-Ma’mun was succeeded by his brother al-Mu‘tasim, who ruled from 833 to 842. His caliphate marks the end of the pivotal period of Byzantine– Muslim relations that followed the death of Harun. Al-Mu‘tasim abandoned Tyana soon after assuming power, but his anger was roused by the Byzantines’ capture of Samosata and Zapetra in 837, and he succeeded in fulfilling the ambitions of his brother by organising a massive three-pronged invasion of Anatolia.His forces crushed the armies of Theophilos at the battle ofDazimon and then besieged and briefly occupied Amorion in 838, not only an important military base, but also the ancestral home of the Amorian dynasty. He thereby dealt a massive blow to the resources and prestige of Theophilos and his dynasty – and to Byzantium in general – and a number of Byzantine prisoners were executed. Although al-Mu‘tasim’s armies were obliged to withdraw to caliphal territories in order to suppress worrisome insurgents, the campaign of 838 revealed major weaknesses in Byzantine military capacity. Al-Mu‘tasim’s newly recruited elite Turkish forces proved their archery skills against the Byzantine soldiers to deadly effect, and the Byzantines were initially unable to resist them.66 Al-Mu‘tasim’s forces also demonstrated their ability to undertake and bring to a successful conclusion sieges of large, well-fortified Byzantine cities such as Amorion.67 Once again, internalMuslim political, religious and military strife rather than Byzantine institutions or imperial decisions brought respite for Byzantium, just as theByzantines’ mood was turning to despair. The 838 campaign marked the zenith of caliphal expeditions across the Taurus mountains into Anatolia. Theophilos and al-Mu‘tasim made peace in 841. The shift of the Abbasids’ main residence from Baghdad to their huge new city of Samarra and the emergence of a powerful separate unit of Turkish guards changed the dynamics of Abbasid power for the worse.68 No future Abbasid caliph would lead in person an invasion from Iraq into Anatolia. Nor would any Abbasid expedition manage to assemble troops on the scale of that of 838. The death of al-Mu‘tasim in 842 marks a turning-point in the caliphate’s offensive capability against Byzantium. His new commanders based at Samarra regarded volunteers for the jihad as a nuisance. In 857 Caliph al-Mutawakkil (847–61) abolished all the fiscal immunities that the thughurs had enjoyed. He did try to mount a huge show-piece campaign when he moved his army and much of the administration westwards to Damascus in 858, but military unrest thwarted his efforts. The assassination of al-Mutawakkil in 861 triggered what is sometimes termed the spell of ‘anarchy’ at Samarra, and Byzantium’s military situation benefited accordingly.69