ABSTRACT
Since his ascension Leo must have had serious concerns about the fidelity of the eastern regions of the empire, conscious as he was that the military threat posed by the caliphate could eventually turn out to be more dangerous than the Bulgarian khaganate. Nor could he afford to have a new front open in the east before putting an end to the Bulgarian invasion. As we know from his career, Leo was well acquainted with the situation on the frontier and probably knew the potential dangers. This explains why he wanted to prevent further troubles by sending his most intimate friends there. It is in this context that we must understand the appointment of Thomas as a tourmarches of the phoideratoi by Leo at the very beginning of his reign (see immediately below).
