 John Kourkouas ( Greek : Ἰωάννης Κουρκούας , fl. circa 915 – 946 ) , also transliterated as Kurkuas or Curcuas , was one of the most important generals of the Byzantine Empire . His success in battles against the Muslim states in the East definitively reversed the course of the centuries @-@ long Byzantine – Arab Wars and began Byzantium 's 10th century " Age of Conquest " . 
