It has been suggested that Isa served as governor of Damascus in 861, but according to Marius Canard this is a confusion with Isa ibn Muhammad al-Nawshari. In 865, according to al-Tabari, he defeated and captured a Kharijite rebel named al-Muwaffaq.[1][2] At the time, he held a post in Syria, since al-Tabari records him asking for aid from the Caliph al-Mutawakkil in preparing a raid against Byzantium, including four ships to be set ready in Tyre.[3] He was probably already governor of Jund Filastin (Palestine) district at the time, a post which he seems to have held, according to Ya'qubi, at the time of the deposition of Caliph al-Musta'in in January 866.[2][4] According to Ya'qubi, Isa was one of the governors who refused to immediately acknowledge the new Caliph, al-Mu'tazz, perhaps because his old patron Bugha still remained loyal to al-Musta'in. This led al-Nawshari to campaign against him, and the two armies clashed by the Jordan River.