Excerpts from Books and Wikipedia
"Basil II, the Bulgar Slayer: The Byzantine emperor Basil II (reigned 976-1025) earned his soubriquet after his 15-year war against the Bulgarian empire culminated in his victory at the Belasica mountains in 1015; some 15,000 prisoners were blinded and sent home in groups of one hundred, each group led by a one-eyed man. The Bulgarian czar Samuel died of shock and Bulgaria was annexed to Byzantium in 1018." [DK Timelines, p. 165] "The two forces met near Kleidion, just north of the Aegean Sea in the old Macedonian lands, on July 29, 1014. Basil's break from the war, his refusal to take revenge on the Fatimid regime, had allowed him to rebuild his army into shattering strength. The Bulgarians were laid waste. A contemporary historian claims that fifteen thousand Bulgarian troops were taken captive and arrayed before the victorious Basil. . . . He ordered ninety-nine of every hundred captives blinded. The hundredth man was left with only one eye so that he could lead his comrades back to Samuel, who had remained back in the capital city of Ohrid. At the sight of his mutilated troops, Samuel--now an old man, veteran of nearly forty years of war--had a heart attack and died." The Byzantines under Basil II took 50 years to conquer Bulgaria. The year 1018 concluded the Byzantine conquest of Bulgaria. [Timeline of Middle Ages]