Battle of Kleidion

The Battle of Kleidion (Ancient Greek: Κλειδίον; or Clidium, after the medieval name of the village of Klyuch, lit. 'key'; also known as the Battle of Belasitsa) took place on 29 July 1014, between the Byzantine Empire and the Bulgarian Empire. It was the culmination of the nearly half-century struggle between the Byzantine Emperor Basil II and the Bulgarian emperor Samuel in the late 10th and early 11th centuries. The result was a decisive Byzantine victory.

The battle took place in the valley between the mountains of Belasitsa and Ograzhden, near the modern Bulgarian village of Klyuch. The decisive encounter occurred on 29 July with an attack in the rear by a force under the Byzantine general Nikephoros Xiphias, who had infiltrated the Bulgarian positions. The ensuing battle was a major defeat for the Bulgarians. Thousands of Bulgarian soldiers were captured and blinded by order of Basil II, who would subsequently be known as the "Bulgar-Slayer". Samuel survived the battle, but died two months later from a heart attack, reportedly brought on by the sight of his blind soldiers.

Although the engagement did not end the First Bulgarian Empire, the Battle of Kleidion reduced its ability to resist Byzantine advances, and it has been considered the pivotal encounter of the war with Byzantium.

The origins of the conflict date back to the 7th century, when the Bulgars under Khan Asparukh established a state along the Danube in one of the provinces of the Eastern Roman Empire. As a result, the Bulgarian state fought a series of wars with Byzantium in order to secure its continued existence.

In 968, Bulgaria was invaded from the north by the Kievan prince Sviatoslav. By that time, the Bulgarian Empire, which had once threatened the existence of Byzantium under the reign of Simeon, had lost much of its power. During the conflict, the Kievan raids were repeatedly defeated by the Byzantines, who were also at war with the Bulgarians, a continuous conflict since the fall of the Bulgarian capital Preslav in 971. This war had resulted in the Bulgarian emperor Boris II being forced to renounce his imperial title in Constantinople, and eastern Bulgaria came under Byzantine rule. The Byzantines assumed that this act would signify the end of independent Bulgaria, but the western Bulgarian lands remained autonomous and under the Comitopuli brothers David, Moses, Aaron and Samuel, resistance against the Byzantines emerged.

When the Byzantine emperor Basil II ascended the throne in 976, he made the destruction of independent Bulgaria his first ambition. Opposing him were the western Bulgarians, now led by Samuel of Bulgaria. Basil II's first campaign was disastrous, the Emperor barely escaping with his life when the Bulgarians annihilated the Byzantine army in the Gates of Trajan Pass in 986. Over the next fifteen years, while Basil was preoccupied with revolts against his rule and the Fatimid threat in the east, Samuel retook most of the previously conquered Bulgarian lands and carried the war into enemy territory in a series of campaigns. However, his invasion of southern Greece, that reached as far as Corinth, resulted in a major defeat in the Battle of Spercheios in 996. The next phase of the war began in 1000, when Basil, having secured his own position, launched a series of offensives against Bulgaria. He secured Moesia, and in 1003, his forces took Vidin. The next year, Basil inflicted a heavy defeat on Samuel in the Battle of Skopie. By 1005, Basil had regained control of Thessaly and parts of southern Macedonia. Over these and the next few years, a regular pattern emerged: the Byzantines would campaign in Bulgaria, laying siege to forts and pillaging the countryside, while the numerically inferior Bulgarians, unable to offer direct opposition, launched diversionary raids in Macedonia and Greece. Despite some successes, these did not achieve any permanent results, nor did they force Basil to abandon his campaigns in Bulgaria. A counter-attack in 1009 failed at the Battle of Kreta, and although the Byzantines themselves did not achieve any decisive success, their methodical war of attrition deprived the Bulgarians of their strongholds and gradually weakened their forces. In the words of Byzantine historian John Skylitzes: "The Emperor Basil II continued to invade Bulgaria each year and destroy and devastate everything on his way. Samuel could not stop him in the open field or engage the Emperor in a decisive battle, and suffered many defeats and began to lose his strength." The culmination of the war came in 1014, when Samuel, at the head of his army, resolved to stop the Byzantine army before it could enter the Bulgarian heartland.

Samuel knew that the Byzantine army would have to invade the country through a series of mountain passes, and so took precautions to bar them. The Bulgarians built ditches along the frontier and fortified many of the valleys and passes with walls and towers, especially the pass of Kleidion on the Struma River which Basil would need to pass through to reach the heart of Bulgaria. Samuel heavily fortified the northern slopes of the Belasitsa mountain to the south and east of Strumitsa Castle. The wide valley of the Strumitsa River was a convenient place for attack and it had been used by Byzantine forces for this purpose in previous years. The Bulgarians disposed a strong guard to keep the pass safe. In addition, the Bulgarian ruler chose Strumitsa for his defensive base — it was located on the road from Thessaloniki leading to Thrace to the east and Ohrid to the west. The rugged terrain to the south was dotted with earthworks and walls guarded by strong Bulgarian units.

Samuel's decision to face Basil II and the bulk of his army at Kleidion was not only prompted by the constant defeats and invasions which had devastated the country, but also by concerns over his authority among the nobility, which had been fatally weakened by Basil's campaigns. In 1005 for example, the governor of the important Adriatic port of Dyrrhachium had surrendered the town to Basil II. To face this threat, Samuel gathered a large army to face the Byzantines, some claiming it numbered as many as 45,000 soldiers. Basil II also prepared carefully, assembling a large army of his own and taking his most experienced commanders, including the governor of Philippopolis (modern Plovdiv), Nicephorus Xiphias, who had conquered the old Bulgarian capitals Pliska and Preslav from Samuel in 1001.^{[citation needed]}