In the absence of the main Byzantine army, the Bulgarians also revolted under Peter IV of Bulgaria. Their timing could not have been better, since Byzantium was still reeling from a bloody coup and a disastrous invasion. Isaac resolved to pacify the Bulgarian rebellion with force and headed a military expedition north. The Byzantine army was ambushed in a way reminiscent of the Battle of Manzikert and of the earlier fiasco at Pliska. The last attempt to enforce Byzantine authority over Bulgaria concurred with Isaac's last genuine attempts at running the Empire; according to scholars, from then on, Isaac's policies were rarely more than reactionary.