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Siege of Serdica
Part of the Byzantine-Bulgarian Wars
DateSpring 809
Result Bulgarian victory
Bulgarian Empire Byzantine Empire
Commanders and leaders
Krum Unknown
Unknown 6,000
Casualties and losses
Unknown 6,000

The siege of Serdica (Bulgarian: Обсадата на Сердика) took place in the spring of 809 at modern Sofia, Bulgaria. As a result, the city was annexed to the Bulgarian State and remained so until the fall of the First Bulgarian Empire.

Historical background

After the destruction of the Avar Khaganate, Khan Krum turned his gaze to the southwest to liberate the Slavs who populated the valley of the Struma River and Macedonia. The main obstacle was the strong Byzantine-held fortress of Serdica (Sofia). The Byzantine Empire was the first to initiate the conflict. In 807, the emperor Nikephoros I marched against Bulgaria but was soon forced to return to Constantinople due to a conspiracy against him. The following year, the Bulgarians, in response to an equestrian raid in the valley of the Struma River, defeated the Byzantines and captured their baggage. In the spring of 809, Khan Krum surprised his enemies with the siege of Serdika.

The siege

In the beginning of 809 Krum besieged the city, but he could not break the resistance of the garrison for several weeks. The food supplies of the city were in decline and the numbers of the garrison were reduced due from the fact that part of the hired mercenaries were released during the winter. The Byzantines were soon forced to give up the city. Khan Krum promised to give safe conduct for the Byzantines on condition they yield the fortress. They agreed and Krum entered Serdica before Easter, but he killed the whole 6,000-strong garrison and some citizens nonetheless. Nikephoros I was unhappy with the Byzantines who escaped from the city and some of them decided to stay with the Bulgarians. One of these was the highly skilled mechanic Evmat who would help Krum later on with the construction of siege machines.


The successful siege was of great importance for Bulgaria because Serdica was a major crossroad in Southeast Europe. It was used as a main base by the later rulers of the country to expand their borders and influence to the south and southwest.