Battle of Ongal
Part of the Byzantine-Bulgarian Wars
Battle of Ongal plan.png

The foundation of the First Bulgarian Empire. The army of Asparukh is in red. The army of Constantine IV is in blue.
DateSummer, 680
The Ongal area probably in Danube delta (present-day Tulcea County, Romania)

Bulgar victory

Seven Slavic tribes
Byzantine Empire
Commanders and leaders
Asparukh Constantine IV
around 10-12,000[1][2][3] "all the themata"[4] from 15 - 25,000[5][6][7]
Casualties and losses
Light Heavy

The Battle of Ongal took place in the summer of 680 in the Ongal area, an unspecified location in and around the Danube delta near the Peuce Island, present-day Tulcea County, Romania. It was fought between the Bulgars, who had recently invaded the Balkans, and the Byzantine Empire, which ultimately lost the battle. The battle was crucial for the creation of the First Bulgarian Empire.

Origins of the conflict

In 632, Khan Kubrat united the Bulgars into the state of Old Great Bulgaria along the coasts of the Black Sea and Caspian Sea. After his death in the 660s his sons divided his kingdom amongst themselves. Batbayan, the eldest son, inherited the throne in Poltava but was defeated by and submitted to the rule of his ambitious relative Cozarig (Kotrag) who had undermined the state's unity by leading his Don-Volga Khazars (Kutrigs) in expansion campaigns extending his empire to the north where Volga Bulgaria would eventually remain. The third son Asparuh marched westward and settled in the Ongal area on the eastern banks of the Danube. Eventually the Avars fought back and after Asparuh consolidated his rule they launched an attack against the Byzantine lands to the south.

During that time the Byzantine Empire was at war with the Arabs who had recently besieged the capital Constantinople. However, in 680 the Byzantines defeated the Arabs and concluded a peace treaty. After this success the emperor Constantine IV was free to move against the Bulgars and led an army against Asparuh. In the meantime the Bulgar leader made an alliance with the Seven Slavic tribes for mutual protection against the Byzantines and formed a federation.

The battle

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According to the Chronicles of Nikephoros I of Constantinople:

The infantry moved in battle lines towards the so called Onglos at the Danube and the fleet was ordered to anchor nearby. The Bulgars, seeing the dense and numerous lines, became desperate, fled in the aforementioned fortification and prepared themselves for defence. In the next 3-4 days nobody of them dared to show up and the Romans did not seek a battle because of the swamps. The filthy people, seeing the Roman weakness, recovered themselves and became bolder. The emperor suffered from a fit of gout and had to return to Messembria to take baths, leaving his generals to start the fighting and to engage them in a battle if they leave their fortifications. Otherwise, to put them under siege and to check their advances. The cavalry, however, spread the rumour that the emperor was deserting them, and fled on their own, without being chased by anybody. The Bulgars, seeing this, attacked and chased them and killed most of them by swords, and many were wounded. And after chasing them up to the Danube, they crossed it.

The Bulgars had built wooden ramparts in the swampy area near the Peuce Island. The marshes forced the Byzantines to attack from a weakened position and in smaller groups, which reduced the strength of their attack. With continuing attacks from the ramparts, the Bulgar defense eventually forced the Byzantines into a rout, followed up by the Bulgar cavalry. Many of the Byzantine soldiers perished. According to popular belief, the emperor had leg pain and went to Mesembria to seek treatment. The troops thought that he fled the battlefield and in turn began fleeing. When the Bulgars realised what was happening, they attacked and defeated their discouraged enemy.


After the victory, the Bulgars advanced south and seized the lands to the north of Stara Planina. In 681 they invaded Thrace defeating the Byzantines again. Constantine IV found himself in a dead-lock and asked for peace.


This battle was a significant moment in European history, as it led to the creation of a powerful state, which was to become a European medieval superpower[8] in the 9th and 10th century along with the Byzantine and Frankish Empires. It became a cultural and spiritual centre of south Slavic Europe through most of the Middle Ages.


Ongal Peak in Tangra Mountains on Livingston Island in the South Shetland Islands, Antarctica is named for the historical Ongal area.


  1. ^ “The Size of Bulgaria’s Medieval Field Armies: A Case Study of Military Mobilization Capacity in the Middle Ages,” by Aleksandar Stoyanov, The Journal of Military History, 83:3 (July 2019): pp. 719-746.
  2. ^ Образуване на българската народност. Димитър Ангелов (Издателство Наука и изкуство, "Векове", София 1971) с. 202—203.
  3. ^ Dennis P. Hupchick, The Bulgarian-Byzantine Wars for Early Medieval Balkan Hegemony: Silver-Lined Skulls and Blinded Armies, Springer, 2017, ISBN 3319562061, p. 49.
  4. ^ The Chronicle of Theophanes Confessor. Byzantine and Near Eastern History, AD 284-813. Oxford, 1997, p. 498
  5. ^ Treadgold, Warren (1997). A History of the Byzantine State and Society. Stanford, California: Stanford University Press. p. 576. ISBN 0-8047-2630-2..
  6. ^ Byzantium in the Seventh Century: The transformation of a Culture, J. F. Haldon, Cambridge University Press, 1997, ISBN 052131917X, стр. 253.
  7. ^ Whittow, Mark (1996). The Making of Byzantium, 600–1025. Berkeley and Los Angeles, California: University of California Press. p. 188. ISBN 978-0-520-20496-6..
  8. ^ Daniel Ziemann: Das Erste bulgarische Reich. Eine frühmittelalterliche Großmacht zwischen Byzanz und Abendland. (German: An early medieval great power between Byzantium and the Occident) In: Online handbook on the history of South-East Europe. Volume I Rule and politics in Southeastern Europe until 1800. Published by the Institute for East and Southeast European Studies of the Leibniz Association, Regensburg 2016