The Battle of Anchialus, 917: Byzantium's bloody disaster

By the numbers
Side	Strength	Losses
Byzantine Empire	A large army	Catastrophic; much of the army destroyed
Bulgaria	A large army under Simeon	Victorious; losses far lighter

By the numbers

Side

Strength

Losses

Byzantine Empire

A large army

Catastrophic; much of the army destroyed

Bulgaria

A large army under Simeon

Victorious; losses far lighter

Quick answer

At the Battle of Anchialus on 20 August 917¹, Tsar Simeon I of Bulgaria crushed a large Byzantine army led by Leo Phokas near the Black Sea coast. The Byzantine attack began well, but a Bulgarian counterattack turned the day into a rout and then a massacre. It was one of the bloodiest and most catastrophic defeats in Byzantine history, and it left Simeon dominant in the Balkans² and dreaming of the imperial throne itself.

Not every great battle of the empire was a victory. At Anchialus a powerful Byzantine army marched out to crush Bulgaria, and was itself destroyed in one of the bloodiest days in the empire's history.

Simeon's Bulgaria

By 917 Tsar Simeon I had made Bulgaria the great power of the Balkans and openly challenged the empire, even claiming an imperial title of his own³. To break him, Constantinople assembled a large army under the general Leo Phokas, while a fleet under Romanos Lekapenos sailed for the Danube.

Byzantine miniature of an emperor and a tsar seated at a table in an arcaded palace while attendants stand by — The young emperor Constantine VII dines with Tsar Simeon of Bulgaria during Simeon's visit to Constantinople in 913, a miniature from the Madrid Skylitzes. Public domain

The Byzantine offensive

The two armies met near Anchialus on the Black Sea coast. At first the Byzantine attack went well and the Bulgarians gave ground⁴, and for a moment it seemed the empire would win the victory it had planned.

The rout

Then Simeon committed his reserves in a sudden counterattack.¹ The Byzantine line, perhaps thrown into confusion, broke and fled. What began as a retreat became a rout, and the Bulgarians cut down the fleeing soldiers in huge numbers along the shore. Leo Phokas escaped, but his army was destroyed.⁴

Medieval miniature of charging horsemen with lances overrunning fallen soldiers and shields — Bulgarian horsemen rout the Byzantine army at Anchialus in 917, as illustrated in the Madrid Skylitzes, a 12th century copy of John Skylitzes' chronicle. Public domain

A Byzantine army marched out to crush Bulgaria, and was itself destroyed on the shore.

The reckoning

The slaughter was so great that, the historian Leo the Deacon wrote some seventy years later, the bones of the fallen could still be seen heaped⁵ at the site. It was among the costliest defeats the empire ever suffered, and it left Byzantium reeling and the Balkans open to Bulgarian power.

Why Anchialus mattered

Anchialus marked the height of Bulgarian military power under Simeon, who afterward threatened Constantinople itself². The empire would need generations, and eventually the campaigns decided at Kleidion in 1014 and completed in 1018, to finally subdue Bulgaria. It stands as a reminder that even the great empire knew catastrophe.

Frequently asked questions

When and where was the Battle of Anchialus?

It was fought on 20 August 917 near Anchialus, on the Black Sea coast of modern Bulgaria.

Who won the Battle of Anchialus?

The First Bulgarian Empire under Tsar Simeon I, decisively; the Byzantine army was destroyed.

Why was Anchialus so significant?

It was one of the bloodiest and most catastrophic defeats in Byzantine history and marked the height of Bulgarian power under Simeon.

How did the Byzantines lose?

Their attack began well, but a Bulgarian counterattack broke their line and turned the battle into a rout and massacre.

What happened afterward?

Simeon dominated the Balkans and threatened Constantinople; Bulgaria was only finally subdued a century later, in Basil II's wars, decided at Kleidion in 1014 and completed in 1018.

Sources and notes

Numbered notes in the text point to the works below.

John V. A. Fine, Jr., The Early Medieval Balkans: A Critical Survey from the Sixth to the Late Twelfth Century (University of Michigan Press, 1983). ↩ a b

Paul Stephenson, Byzantium's Balkan Frontier: A Political Study of the Northern Balkans, 900-1204 (Cambridge University Press, 2000). ↩ a b

Encyclopaedia Britannica, “Byzantine-Bulgarian Wars” ↩

Wikipedia, “Battle of Achelous (917)” ↩ a b

Leo the Deacon, History, trans. Alice-Mary Talbot and Denis F. Sullivan, The History of Leo the Deacon (Dumbarton Oaks, 2005), Remark that heaps of bones could still be seen near Anchialus, where the fleeing Roman army was cut down. ↩