Following the death of Constantine V in 775, his successors refused the military policy of the Isaurian dynasty which led to a number of adverse consequences. The army got involved into the confrontation between religious and political groups. As a result, by the mid-780s a crisis broke out in the military and administrative system of Byzantium. After the dissolution of most of the regular tagmata, defensive and offensive operations were compelled to conduct militias of five eastern provinces (Opsikion, Thrakesion, Anatolikon, Armeniakon, Kibyrrhaioton). In the simultaneous war against Arabs and Bulgarians, this task proved to be impossible for them. According to the author, the military policy of the successors of Constantine V forced the empire to wage heavy defensive wars until the 820-830s.