 Complete the following phrase:  Abbasid calculations proved correct, as the two brothers spent much time quarrelling with each other. In 841, for instance, Bagrat had the Armenian bishops depose the Catholicos of Armenia, John IV, but he was promptly re-installed in his see by Smbat with the assistance of the other princes. Nevertheless, the Armenian princes were able to use the Caliphates preoccupation with the Khurramite rebellion of Babak Khorramdin to achieve a significant degree of autonomy during this period. Smbat, who had spent time at the caliphal court as a hostage, was more circumspect about openly challenging Arab power than his brother, but both were ultimately too weak to seriously threaten Abbasid predomice for the time being. Thus Bagrat participated in the 