Battle of Kleidion

In a mountain valley near the village of Klyuch, in what is now south-western Bulgaria, the Byzantine emperor Basil II broke the main army of Tsar Samuel of Bulgaria on 29 July 1014. Also called the Battle of Belasitsa, after the range above the valley, it was the turning point of a war that had lasted for decades. The mass blinding of the captured Bulgarians that followed earned Basil his famous nickname, "the Bulgar-slayer".

Bulgaria had lost its eastern lands to Byzantium in 971, but in the west resistance continued under four brothers, of whom Samuel became the leader. Basil came to the throne in 976 and set out to destroy Bulgarian independence. His first campaign ended in disaster in 986, when his army was wiped out at the Gates of Trajan pass and he barely escaped. For years afterwards Samuel recovered lost territory and raided deep into Greece, until a heavy defeat at the Spercheios river in 996.

From 1000 Basil went back on the offensive. He took Vidin in 1003, beat Samuel near Skopje the next year and recovered Thessaly. Each summer his armies besieged forts and plundered the countryside, while the outnumbered Bulgarians answered with raids into Byzantine territory. This war of attrition steadily stripped Samuel of strongholds and of the loyalty of his nobles.

Samuel decided to stop the next invasion before it reached the Bulgarian heartland. He dug ditches and built walls and towers across the mountain routes, above all at the Kleidion pass on the Struma, the road Basil would need to take, and based himself at the fortress of Strumitsa. According to some accounts he gathered as many as 45,000 men. Basil assembled a large army of his own, with his most experienced generals.

Marching from Constantinople, the Byzantines found the valley near Klyuch closed by a thick wooden wall. Their first assaults were thrown back with heavy losses by a defending force estimated at 15,000 to 20,000. Samuel tried to draw Basil away by sending an army south under Nestoritsa towards Thessalonica, but the city's governor, Theophylaktos Botaneiates, defeated it and marched north to join the emperor.

Basil then sent his general Nikephoros Xiphias with a detachment along a steep path around the Belasitsa mountain. On 29 July Xiphias fell on the Bulgarians from behind. As the defenders turned to meet him, Basil broke through the wall. Thousands of Bulgarians were killed in the rout. Samuel, coming to help, was caught in fierce fighting near Mokrievo and escaped only because his son Gabriel Radomir gave him his own horse.

The Byzantine historian John Skylitzes put the number of prisoners at 15,000; another Byzantine writer gave 14,000, and a later Bulgarian translation of the Manasses Chronicle 8,000. Modern historians such as Vasil Zlatarski consider the higher figures exaggerated. Basil had the captives divided into groups of a hundred and blinded, leaving one man in each group with a single eye to lead the rest home. The act is often linked to the death of Botaneiates, killed soon afterwards in a Bulgarian ambush near Strumitsa, and blinding was also a customary Byzantine punishment for rebels. Samuel died of a heart attack on 6 October 1014, reportedly after seeing his returning soldiers.

The victory was not immediately complete. The Byzantine setback near Strumitsa forced Basil to lift his siege there, and fighting went on for four more years. Samuel's successors could not halt the decline, however, and many provincial governors surrendered. In 1018 Bulgaria was fully conquered and became a Byzantine province, which it remained until the rising of the Asen brothers in 1185. The empire's frontier once more reached the Danube, and the Serbs and Croats acknowledged Byzantine supremacy.

Our 1000 map shows Samuel's Bulgarian state still holding much of the interior of the Balkans, including today's North Macedonia; by the 1100 map the Byzantine Empire controls the whole region up to the Danube.