Basil II earned the nickname Bulgar Slayer after decades of wars against the First Bulgarian Empire. His campaigns eventually brought most of Bulgaria under Byzantine rule and made him one of the empire’s most formidable medieval rulers.
Basil became sole emperor in 976 and faced the powerful Bulgarian ruler Samuel. The conflict continued for decades, with mountain fortresses, raids, sieges, and repeated Byzantine setbacks. Basil gradually improved his position through military persistence and pressure on Bulgarian strongholds.
The nickname is especially associated with the Byzantine victory at Kleidion in 1014. Byzantine sources say that Basil ordered captured Bulgarian soldiers to be blinded, leaving one guide for every hundred men. The dramatic story may have been exaggerated, but it became central to the later image of the Bulgar Slayer. Samuel reportedly died after seeing the survivors.
Basil’s conquest was completed after further resistance, and Bulgaria was incorporated into the Byzantine Empire by 1018. The epithet became common later, so it should not be treated as proof that every detail of the blinding account is certain.