Himerios can be retired to grant 1 promotion level and +25% combat experience to a military naval unit.
Byzantium was a maritime empire. Despite the Empire’s rich holdings in Anatolia (at least for a time), the Byzantines relied upon a strong navy for security. This became doubly important when the Byzantines began to compete with an ascendant Arab presence in the Mediterranean. While the land-based battles and sieges of the Crusades loom large in the Western European imagination, battles between the Byzantines and a growing Muslim Caliphate were common throughout the medieval period. These battles were often played out on water. As a result, admirals rose to prominence on both sides.
Himerios was a Byzantine admiral appointed to command the Empire’s fleet in 904. At this point, the Abbasid Caliphate was expanding into the Mediterranean with the help of Leo of Tripoli, a Greek renegade and the commander of the Abbasid navy. Leo and Himerios sought to outmaneuver each other, and, as Himerios headed off Leo’s fleet as it sailed towards Constantinople, Leo turned and sacked the Empire’s second-largest city, Thessalonica, instead. Two years later, Himerios would have his revenge, as a victory on St. Thomas’s Day in 906 sparked a string of Byzantine wins across the Mediterranean coast, in Syria and Cyprus.
In the end, though, Leo proved too canny for Himerios. Rushing back to the capital following the illness of the Emperor, Himerios fell into a trap laid by Leo and the Abbasid fleet. While Himerios escaped, his fleet was destroyed, and the new Emperor promptly dismissed him. He fled to a monastery and died six months later.