As Domestic of the Schools, the Byzantine army's commander-in-chief, he led a large-scale campaign against the Bulgarians in 917, but was heavily defeated at the battles of Acheloos and Katasyrtai. He then plotted to seize the throne from the young Byzantine emperor Constantine VII (r. 913–959), but was outmaneuvered by the admiral Romanos Lekapenos, who managed to become guardian and later father-in-law of the Emperor.