With Harun al-Rashid's accession in 786, the raids launched over the next two years were relatively minor affairs; the first great invasion of the new reign occurred in 788, when a large expeditionary force crossed the Cilician Gates into the Anatolic Theme.[3][4] Although the raid is not mentioned in Arabic sources, its description by the Byzantine chronicler Theophanes the Confessor points to a major invasion, as it was confronted by the forces of the two most powerful Byzantine thematic armies, those of the Anatolic Theme itself and of the Opsician Theme.[5]