First Bulgarian Empire - Expansion

After the Internal instability and struggle for survival period of the First Bulgarian Empire and the death of Constantine V,  the devastation brought to the country by his nine campaigns firmly rallied the Slavs behind the Bulgars and greatly increased the dislike of the Byzantines, turning Bulgaria into a hostile neighbour. The hostilities continued until 792 when Khan Kardam (r. 777–803) achieved an important victory in the battle of Marcelae, forcing the Byzantines once again to pay tribute to the Khans. As a result of the victory, the crisis was finally overcome, and Bulgaria entered the new century stable, stronger, and consolidated.

 Church of St. Sophia, Ohrid

During the reign of Khan Krum (r. 803–814) Bulgaria doubled in size and expanded southward and to the northwest, occupying the lands along the middle Danube and Transylvania. Between 804 and 806 the Bulgarian armies thoroughly eliminated the Avar Khaganate, which had suffered a crippling blow by the Franks in 796, and a border with the Frankish Empire was established along the middle Danube or Tisza.

A 14th century depiction of Krum

In 808 they raided the valley of the Struma River, defeating a Byzantine army, and in 809 captured the important city Serdica. In 811 the Byzantine Emperor Nicephorus I launched a massive offensive against Bulgaria, seized, plundered and burned down the capital Pliska but on the way back the Byzantine army was decisively defeated in the battle of the Varbitsa Pass. Nicephorus I himself was slain along with most of his troops and his skull was lined with silver and used as a drinking cup.

Khan Krum feasts while a servant brings the skull of Nikephoros I fashioned into a drinking cup

Khan Krum took the initiative and in 812 moved the war towards Thrace, capturing the key Black Sea port of Messembria and defeating the Byzantines once more at Versinikia in 813 before proposing a generous peace settlement. However, during the negotiations the Byzantines attempted to assassinate Krum and in response Bulgarians pillaged Eastern Thrace. He planned to capture Constantinople but due to his death on 14 April 814, the plan was not executed.

Makri Harbor, Messembria region

Khan Krum's successor Khan Omurtag (r. 814–831) concluded a 30-year peace treaty with the Byzantines. Omurtag started in 814 persecution of Christians, in particular against the Byzantine prisoners of war settled north of the Danube. The expansion to the south and south-west continued under Omurtag's successors under the guidance of the capable kavhan (First Minister) Isbul. During the short reign of Khan Malamir (r. 831–836), the important city of Philippopolis (Plovdiv) was incorporated into the country.

Bulgar soldiers slaughter Christians

Under Khan Presian (r. 836–852), the Bulgarians took most of Macedonia, and the borders of the country reached the Adriatic Sea near Valona and Aegean Sea. With this, Bulgaria had become the dominant power in the Balkans. The advances further west was blocked by the development of a new Slavic state under Byzantine patronage, the Principality of Serbia. Between 839 and 842 the Bulgarians waged war on the Serbs but did not make any progress.

Adriatic Sea, Croatia

The reign of Boris I (r. 852–889) began with numerous setbacks. For ten years the country fought against the Byzantine Empire, Eastern Francia, Great Moravia, the Croats and the Serbs forming several unsuccessful alliances and changing sides. Yet, despite all military setbacks and natural disasters the skilful diplomacy of Boris I prevented any territorial losses and kept the realm intact. Boris I converted to Christianity in 864.

Depiction in the Manases Chronicle of Boris I' baptism

Boris I dealt ruthlessly with the opposition to the Christianisation of Bulgaria, crushing a revolt of the nobility in 866 and overthrowing his own son Vladimir (r. 889–893) after he attempted to restore the traditional religion. In 893 he convened the Council of Preslav where it was decided that the capital of Bulgaria was to be moved from Pliska to Preslav, the Byzantine clergy was to be banished from the country and replaced with Bulgarian clerics. Bulgaria was to become the principle threat for the stability and security of the Byzantine Empire in the 10th century.

Preslav