 Complete the following phrase:  In 812 Michael I reopened negotiations with the Franks, and recognized Charlemagne as imperator and basileus Emperor, but not Emperor of the Romans. In exchange for that recognition, Venice was returned to the Empire. However, under the influence of Theodore, Michael rejected the peace terms offered by Krum and provoked the capture of Mesembria Nesebar by the Bulgarians. After an initial success in spring 813, Michaels army prepared for a major engagement at 