The battle of Marcellae took place in 756 between the armies of the First Bulgarian Empire

First Bulgarian Empire

The First Bulgarian Empire was a medieval Bulgarian state founded in the north-eastern Balkans in c. 680 by the Bulgars, uniting with seven South Slavic tribes...

 and the Byzantine Empire

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 at Markeli

Markeli

Markeli was a medieval Byzantine and Bulgarian frontier stronghold, the ruins of which are located in Karnobat Municipality, Burgas Province, southeastern Bulgaria. Dating to Late Antiquity, the castle lay some from the modern town of Karnobat...

, near the town of Karnobat

Karnobat

Karnobat is a town in the Burgas Province, Southeastern Bulgaria. It is the administrative centre of the homonymous Karnobat Municipality. As of December 2009, the town has a population of 18,480 inhabitants.-Geography:...

 in south eastern Bulgaria

Bulgaria

Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...

. The result was a Byzantine victory.

Origins of the conflict

In 755, the long peace between Bulgaria and the Byzantine Empire came to an end. This was mainly because, after significant victories over the Arabs, the Byzantine Emperor Constantine V

Constantine V

Constantine V was Byzantine emperor from 741 to 775; ); .-Early life:...

 began to fortify his border with Bulgaria. To this aim he resettled heretics from Armenia

Byzantine Armenia

Byzantine Armenia is the name given to the Armenian part of the Byzantine Empire. The size of the territory varied over time, depending on the degree of control the Byzantines had over Armenia....

 and Syria in Thrace

Thrace

Thrace is a historical and geographic area in southeast Europe. As a geographical concept, Thrace designates a region bounded by the Balkan Mountains on the north, Rhodope Mountains and the Aegean Sea on the south, and by the Black Sea and the Sea of Marmara on the east...

. Khan Kormisosh

Kormisosh of Bulgaria

Kormisosh was a ruler of Bulgaria during the 8th century.The Namelist of Bulgarian Rulers states that he belonged to the Ukil clan and ruled for 17 years. According to the chronology developed by Moskov, Kormisosh would have reigned from 737 to 754...

 took those actions, and the construction of a new fortress along the border, as a breach of the Treaty of 716, signed by Tervel

Tervel of Bulgaria

Khan Tervel also called Tarvel, or Terval, or Terbelis in some Byzantine sources, was the Emperor of the Bulgarians at the beginning of the 8th century. In 705 he received the title Caesar which was a precedent in history. He was probably a Christian like his grandfather Khan Kubrat...

. The Bulgarian ruler sent envoys to ask for tribute for the new fortresses. After the refusal of the Byzantine Emperor, the Bulgarian army

Medieval Bulgarian Army

The medieval Bulgarian army was the primary military body of the First and the Second Bulgarian Empires. During the first decades after the foundation of the country, the army consisted of a Bulgar cavalry and a Slavic infantry. The core of the Bulgarian army was the heavy cavalry, which consisted...

 invaded Thrace. Looting everything on their way, the Bulgarians reached the outskirts of Constantinople

Constantinople

Constantinople was the capital of the Roman, Eastern Roman, Byzantine, Latin, and Ottoman Empires. Throughout most of the Middle Ages, Constantinople was Europe's largest and wealthiest city.-Names:...

, where they were engaged and defeated by Byzantine troops.

Battle

In the next year, Constantine V organized a large campaign against Bulgaria which was now ruled by a new Khan, Vinekh

Vinekh of Bulgaria

Vinekh was ruler of Bulgaria in the mid-8th century.According to the Namelist of Bulgarian Rulers, Vinekh reigned for 7 years and was a member of the Uokil clan . According to the chronology developed by Moskov, Vinekh would have reigned 754–762...

. An army was sent with 500 ships which plundered the area around the Danube delta

Danube Delta

The Danube Delta is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Romania , while its northern part, on the left bank of the Chilia arm, is situated in Ukraine . The approximate surface is...

. The Emperor himself, leading the main force, advanced into Thrace, and was engaged by the Bulgarians at the border castle of Marcellae. The details of the battle are unknown but it resulted in a victory for Constantine V. In order to stop the invasion, the Bulgarians sent hostages in Constantinople. However, three years later (759), Constantine invaded Bulgaria once more, but suffered a crushing defeat in the battle of the Rishki Pass

Battle of the Rishki Pass

The Battle of the Rishki Pass took place in the pass of the same name, in Stara Planina, Bulgaria in 759. It was fought between the Bulgarian Empire and the Byzantine Empire...

.