not mentioned in the sources during this period. Certainly at the time of the outbreak of the great rebellion of Thomas the Slav, the of the Armeniacs was Olbianos, while the Anatolics joined the rebellion. Manuel himself, however, evidently remained loyal to Michael, and it was probably the latter who raised him to the high court rank of . The editors of the Prosopographie der mittelbyzantinischen Zeit suggest that Manuel may have been recalled by Michael to Constantinople, especially if the marriage of Michael's son and heir Theophilos () and Manuel's niece Theodora took place around 821, as suggested by E.W. Brooks, and not around 830, as suggested by Treadgold. Escape to the Caliphate In 829, either some time before (according to Theophanes Continuatus, followed by E.W. Brooks and the Prosopographie der mittelbyzantinischen Zeit and others) or shortly after (according to Symeon Logothetes, accepted by Treadgold, the Oxford Dictionary of Byzantium and others) the death of Michael and the accession of Theophilos, Manuel defected to the Abbasids as a result of machinations at court: the logothetes tou dromou (foreign minister) Myron had accused him to the new emperor of plotting to seize the throne. Using the carriages of the imperial post, he crossed Asia Minor in haste and offered his services to Caliph al-Ma'mun (), on condition that he would not be forced to convert to Islam. According to the 13th-century historian Vardan Areveltsi, so great was Ma'mun's joy at this defection that he gave Manuel a daily salary of 1,306 silver s, and continually presented him with gifts. Theophilos, in turn, was hesitant to believe the accusations, and was eventually convinced by the (chamberlain) Leo Chamodrakon and the John the Grammarian of his general's innocence. He therefore resolved to get Manuel to return, and sent John the Grammarian to Baghdad on a diplomatic mission in the winter of 829/830, ostensibly in order to announce his accession. John was indeed able to see Manuel in private and offered him the Emperor's pardon, which Manuel seemed to accept, although for the time being, Manuel remained publicly loyal to his Abbasid allegiance. In the summer of 830, Manuel participated in an Abbasid expedition against the Khurramite rebels of Babak Khorramdin in Adharbayjan, alongside a contingent of Byzantine captives. The campaign was nominally led by Ma'mun's own son, Abbas, but it is likely, according to Treadgold, that the more experienced Manuel was the