commands (tourmai or droungoi), a fact pointed out by Emperor Constantine VII Porphyrogennetos (r. 913–959) as a sign of inferior status. Consequently, their commanding domestikos held the lowest rank of all provincial stratēgoi in the imperial hierarchy. As with the other themata, for the administration of his duties as governor of the province, the domestikos was assisted by a deputy (topotērētēs), a chief financial official (chartoularios) and a secretariat headed by a prōtokankellarios. The rural districts of the thema were raided by Seljuk Turks after the Battle of Manzikert, but Nicomedia was retained, and the area secured again under Emperor Alexios I Komnenos (r. 1081–1118) with the help of the First Crusade. The area was occupied by the Latins after the dissolution of the Empire by the Fourth Crusade in 1204, but the thema was re-established by John III Vatatzes when he retook the region in 1240, and survived until the area was gradually conquered by the rising Ottoman beylik in the first half of the 14th century. References Sources Byzantine Bithynia Military units and formations of the Byzantine Empire Cavalry units and formations Themes of the Byzantine Empire Military units and formations established in the 6th century Gothic warriors Byzantine mercenaries