July 29, 1014 the Bulgarian army is defeated by the troops of the Byzantine Emperor Basil II. The Battle of Belasitsa, also known as the Battle of Klyuch or the Battle of Klydion is the culmination of the duel between the Bulgarian Tsar Samuil and the Byzantine Emperor Basil II, which lasted for decades in the late 10th century and early 11th century.
The battle ends with a heavy defeat for the Bulgarians. According to the testimonies of various medieval chroniclers, the number of dead was significant, and those captured were blinded by order of Basil II, later called the "Bulgar Killer".
At the beginning of this duel, Samuil had the upper hand, but from 1001, when Byzantium shook off its internal strife and its conflict with the Arabs, the Bulgarians began to lose their supremacy and were forced to fight for their independence. In order to stop enemy invasions, they built an extensive fortification system, blocking the mountain passes and other roads to the interior of the state.
During his next campaign in the summer of 1014, Basil II was stopped in front of one of these fortifications - the dema fortress, erected by Samuil in the Klyuchka Gorge between the Belasitsa and Ograzhden mountains, near the present-day village of Klyuch. The Bulgarian troops repelled repeated attempts by the Byzantines to capture the barrier, but on July 29 they were suddenly attacked in the rear by the detachment of Nicephorus Xiphius, who managed to bypass their positions along mountain paths.
The battle ended with a heavy defeat for the Bulgarians. According to the testimonies of various medieval chroniclers, the number of dead was significant, and those taken prisoner were blinded by order of Basil II, later called the "Bulgar Killer". Tsar Samuil escaped death in the battle itself, but died two months later - on October 6, 1014, after suffering a heart attack at the sight of his blinded fighters.