Answer
At Myriokephalon, Manuel I Komnenos, the Byzantine Emperor, faced a crushing defeat towards the end of his rule. The Seljuk Turks, led by Sultan Kilij Arslan II, dealt a severe blow to the Byzantine army in 1176. This loss not only weakened the Byzantine Empire's military strength but also marked a significant turning point, as it eroded their dominance in Asia Minor and accelerated the decline of Byzantine power.