 Nikephoros Xiphias ( Greek : Νικηφόρος <unk> , fl. ca . 1000 – 1028 ) was a Byzantine military commander during the reign of Emperor Basil II . He played a distinguished role in the Byzantine conquest of Bulgaria , and was instrumental in the decisive Byzantine victory at the Battle of Kleidion in 1014 . In 1022 he led an unsuccessful rebellion against Basil II , and was disgraced , tonsured and exiled . He is last mentioned in 1028 , when he was recalled from exile and retired to a monastery . 
